diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DocBook/kernel-api.tmpl | 54 | ||||
| -rw-r--r-- | Documentation/fb/gxfb.txt | 52 | ||||
| -rw-r--r-- | Documentation/fb/intelfb.txt | 2 | ||||
| -rw-r--r-- | Documentation/fb/lxfb.txt | 52 | ||||
| -rw-r--r-- | Documentation/fb/metronomefb.txt | 16 | ||||
| -rw-r--r-- | Documentation/fb/modedb.txt | 4 | ||||
| -rw-r--r-- | Documentation/feature-removal-schedule.txt | 9 | ||||
| -rw-r--r-- | Documentation/filesystems/Locking | 3 | ||||
| -rw-r--r-- | Documentation/filesystems/tmpfs.txt | 12 | ||||
| -rw-r--r-- | Documentation/filesystems/vfat.txt | 15 | ||||
| -rw-r--r-- | Documentation/gpio.txt | 10 | ||||
| -rw-r--r-- | Documentation/kprobes.txt | 51 | ||||
| -rw-r--r-- | Documentation/md.txt | 6 | ||||
| -rw-r--r-- | Documentation/powerpc/booting-without-of.txt | 33 | ||||
| -rw-r--r-- | Documentation/spi/spidev | 168 | ||||
| -rw-r--r-- | Documentation/spi/spidev_fdx.c | 158 | ||||
| -rw-r--r-- | Documentation/vm/numa_memory_policy.txt | 281 |
17 files changed, 655 insertions, 271 deletions
diff --git a/Documentation/DocBook/kernel-api.tmpl b/Documentation/DocBook/kernel-api.tmpl index 488dd4a4945b..617c2d979975 100644 --- a/Documentation/DocBook/kernel-api.tmpl +++ b/Documentation/DocBook/kernel-api.tmpl @@ -645,4 +645,58 @@ X!Idrivers/video/console/fonts.c !Edrivers/i2c/i2c-core.c </chapter> + <chapter id="clk"> + <title>Clock Framework</title> + + <para> + The clock framework defines programming interfaces to support + software management of the system clock tree. + This framework is widely used with System-On-Chip (SOC) platforms + to support power management and various devices which may need + custom clock rates. + Note that these "clocks" don't relate to timekeeping or real + time clocks (RTCs), each of which have separate frameworks. + These <structname>struct clk</structname> instances may be used + to manage for example a 96 MHz signal that is used to shift bits + into and out of peripherals or busses, or otherwise trigger + synchronous state machine transitions in system hardware. + </para> + + <para> + Power management is supported by explicit software clock gating: + unused clocks are disabled, so the system doesn't waste power + changing the state of transistors that aren't in active use. + On some systems this may be backed by hardware clock gating, + where clocks are gated without being disabled in software. + Sections of chips that are powered but not clocked may be able + to retain their last state. + This low power state is often called a <emphasis>retention + mode</emphasis>. + This mode still incurs leakage currents, especially with finer + circuit geometries, but for CMOS circuits power is mostly used + by clocked state changes. + </para> + + <para> + Power-aware drivers only enable their clocks when the device + they manage is in active use. Also, system sleep states often + differ according to which clock domains are active: while a + "standby" state may allow wakeup from several active domains, a + "mem" (suspend-to-RAM) state may require a more wholesale shutdown + of clocks derived from higher speed PLLs and oscillators, limiting + the number of possible wakeup event sources. A driver's suspend + method may need to be aware of system-specific clock constraints + on the target sleep state. + </para> + + <para> + Some platforms support programmable clock generators. These + can be used by external chips of various kinds, such as other + CPUs, multimedia codecs, and devices with strict requirements + for interface clocking. + </para> + +!Iinclude/linux/clk.h + </chapter> + </book> diff --git a/Documentation/fb/gxfb.txt b/Documentation/fb/gxfb.txt new file mode 100644 index 000000000000..2f640903bbb2 --- /dev/null +++ b/Documentation/fb/gxfb.txt @@ -0,0 +1,52 @@ +[This file is cloned from VesaFB/aty128fb] + +What is gxfb? +================= + +This is a graphics framebuffer driver for AMD Geode GX2 based processors. + +Advantages: + + * No need to use AMD's VSA code (or other VESA emulation layer) in the + BIOS. + * It provides a nice large console (128 cols + 48 lines with 1024x768) + without using tiny, unreadable fonts. + * You can run XF68_FBDev on top of /dev/fb0 + * Most important: boot logo :-) + +Disadvantages: + + * graphic mode is slower than text mode... + + +How to use it? +============== + +Switching modes is done using gxfb.mode_option=<resolution>... boot +parameter or using `fbset' program. + +See Documentation/fb/modedb.txt for more information on modedb +resolutions. + + +X11 +=== + +XF68_FBDev should generally work fine, but it is non-accelerated. + + +Configuration +============= + +You can pass kernel command line options to gxfb with gxfb.<option>. +For example, gxfb.mode_option=800x600@75. +Accepted options: + +mode_option - specify the video mode. Of the form + <x>x<y>[-<bpp>][@<refresh>] +vram - size of video ram (normally auto-detected) +vt_switch - enable vt switching during suspend/resume. The vt + switch is slow, but harmless. + +-- +Andres Salomon <dilinger@debian.org> diff --git a/Documentation/fb/intelfb.txt b/Documentation/fb/intelfb.txt index da5ee74219e8..27a3160650a4 100644 --- a/Documentation/fb/intelfb.txt +++ b/Documentation/fb/intelfb.txt @@ -14,6 +14,8 @@ graphics devices. These would include: Intel 915GM Intel 945G Intel 945GM + Intel 965G + Intel 965GM B. List of available options diff --git a/Documentation/fb/lxfb.txt b/Documentation/fb/lxfb.txt new file mode 100644 index 000000000000..38b3ca6f6ca7 --- /dev/null +++ b/Documentation/fb/lxfb.txt @@ -0,0 +1,52 @@ +[This file is cloned from VesaFB/aty128fb] + +What is lxfb? +================= + +This is a graphics framebuffer driver for AMD Geode LX based processors. + +Advantages: + + * No need to use AMD's VSA code (or other VESA emulation layer) in the + BIOS. + * It provides a nice large console (128 cols + 48 lines with 1024x768) + without using tiny, unreadable fonts. + * You can run XF68_FBDev on top of /dev/fb0 + * Most important: boot logo :-) + +Disadvantages: + + * graphic mode is slower than text mode... + + +How to use it? +============== + +Switching modes is done using lxfb.mode_option=<resolution>... boot +parameter or using `fbset' program. + +See Documentation/fb/modedb.txt for more information on modedb +resolutions. + + +X11 +=== + +XF68_FBDev should generally work fine, but it is non-accelerated. + + +Configuration +============= + +You can pass kernel command line options to lxfb with lxfb.<option>. +For example, lxfb.mode_option=800x600@75. +Accepted options: + +mode_option - specify the video mode. Of the form + <x>x<y>[-<bpp>][@<refresh>] +vram - size of video ram (normally auto-detected) +vt_switch - enable vt switching during suspend/resume. The vt + switch is slow, but harmless. + +-- +Andres Salomon <dilinger@debian.org> diff --git a/Documentation/fb/metronomefb.txt b/Documentation/fb/metronomefb.txt index b9a2e7b7e838..237ca412582d 100644 --- a/Documentation/fb/metronomefb.txt +++ b/Documentation/fb/metronomefb.txt @@ -1,7 +1,7 @@ Metronomefb ----------- Maintained by Jaya Kumar <jayakumar.lkml.gmail.com> -Last revised: Nov 20, 2007 +Last revised: Mar 10, 2008 Metronomefb is a driver for the Metronome display controller. The controller is from E-Ink Corporation. It is intended to be used to drive the E-Ink @@ -11,20 +11,18 @@ display media here http://www.e-ink.com/products/matrix/metronome.html . Metronome is interfaced to the host CPU through the AMLCD interface. The host CPU generates the control information and the image in a framebuffer which is then delivered to the AMLCD interface by a host specific method. -Currently, that's implemented for the PXA's LCDC controller. The display and -error status are each pulled through individual GPIOs. +The display and error status are each pulled through individual GPIOs. -Metronomefb was written for the PXA255/gumstix/lyre combination and -therefore currently has board set specific code in it. If other boards based on -other architectures are available, then the host specific code can be separated -and abstracted out. +Metronomefb is platform independent and depends on a board specific driver +to do all physical IO work. Currently, an example is implemented for the +PXA board used in the AM-200 EPD devkit. This example is am200epd.c Metronomefb requires waveform information which is delivered via the AMLCD interface to the metronome controller. The waveform information is expected to be delivered from userspace via the firmware class interface. The waveform file can be compressed as long as your udev or hotplug script is aware of the need -to uncompress it before delivering it. metronomefb will ask for waveform.wbf -which would typically go into /lib/firmware/waveform.wbf depending on your +to uncompress it before delivering it. metronomefb will ask for metronome.wbf +which would typically go into /lib/firmware/metronome.wbf depending on your udev/hotplug setup. I have only tested with a single waveform file which was originally labeled 23P01201_60_WT0107_MTC. I do not know what it stands for. Caution should be exercised when manipulating the waveform as there may be diff --git a/Documentation/fb/modedb.txt b/Documentation/fb/modedb.txt index 4fcdb4cf4cca..ec4dee75a354 100644 --- a/Documentation/fb/modedb.txt +++ b/Documentation/fb/modedb.txt @@ -125,8 +125,12 @@ There may be more modes. amifb - Amiga chipset frame buffer aty128fb - ATI Rage128 / Pro frame buffer atyfb - ATI Mach64 frame buffer + pm2fb - Permedia 2/2V frame buffer + pm3fb - Permedia 3 frame buffer + sstfb - Voodoo 1/2 (SST1) chipset frame buffer tdfxfb - 3D Fx frame buffer tridentfb - Trident (Cyber)blade chipset frame buffer + vt8623fb - VIA 8623 frame buffer BTW, only a few drivers use this at the moment. Others are to follow (feel free to send patches). diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 448729fcaeb1..599fe55bf297 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -128,15 +128,6 @@ Who: Arjan van de Ven <arjan@linux.intel.com> --------------------------- -What: vm_ops.nopage -When: Soon, provided in-kernel callers have been converted -Why: This interface is replaced by vm_ops.fault, but it has been around - forever, is used by a lot of drivers, and doesn't cost much to - maintain. -Who: Nick Piggin <npiggin@suse.de> - ---------------------------- - What: PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment When: October 2008 Why: The stacking of class devices makes these values misleading and diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 42d4b30b1045..c2992bc54f2f 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -511,7 +511,6 @@ prototypes: void (*open)(struct vm_area_struct*); void (*close)(struct vm_area_struct*); int (*fault)(struct vm_area_struct*, struct vm_fault *); - struct page *(*nopage)(struct vm_area_struct*, unsigned long, int *); int (*page_mkwrite)(struct vm_area_struct *, struct page *); locking rules: @@ -519,7 +518,6 @@ locking rules: open: no yes close: no yes fault: no yes -nopage: no yes page_mkwrite: no yes no ->page_mkwrite() is called when a previously read-only page is @@ -537,4 +535,3 @@ NULL. ipc/shm.c::shm_delete() - may need BKL. ->read() and ->write() in many drivers are (probably) missing BKL. -drivers/sgi/char/graphics.c::sgi_graphics_nopage() - may need BKL. diff --git a/Documentation/filesystems/tmpfs.txt b/Documentation/filesystems/tmpfs.txt index 145e44086358..222437efd75a 100644 --- a/Documentation/filesystems/tmpfs.txt +++ b/Documentation/filesystems/tmpfs.txt @@ -92,6 +92,18 @@ NodeList format is a comma-separated list of decimal numbers and ranges, a range being two hyphen-separated decimal numbers, the smallest and largest node numbers in the range. For example, mpol=bind:0-3,5,7,9-15 +NUMA memory allocation policies have optional flags that can be used in +conjunction with their modes. These optional flags can be specified +when tmpfs is mounted by appending them to the mode before the NodeList. +See Documentation/vm/numa_memory_policy.txt for a list of all available +memory allocation policy mode flags. + + =static is equivalent to MPOL_F_STATIC_NODES + =relative is equivalent to MPOL_F_RELATIVE_NODES + +For example, mpol=bind=static:NodeList, is the equivalent of an +allocation policy of MPOL_BIND | MPOL_F_STATIC_NODES. + Note that trying to mount a tmpfs with an mpol option will fail if the running kernel does not support NUMA; and will fail if its nodelist specifies a node which is not online. If your system relies on that diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt index fcc123ffa252..2d5e1e582e13 100644 --- a/Documentation/filesystems/vfat.txt +++ b/Documentation/filesystems/vfat.txt @@ -17,6 +17,21 @@ dmask=### -- The permission mask for the directory. fmask=### -- The permission mask for files. The default is the umask of current process. +allow_utime=### -- This option controls the permission check of mtime/atime. + + 20 - If current process is in group of file's group ID, + you can change timestamp. + 2 - Other users can change timestamp. + + The default is set from `dmask' option. (If the directory is + writable, utime(2) is also allowed. I.e. ~dmask & 022) + + Normally utime(2) checks current process is owner of + the file, or it has CAP_FOWNER capability. But FAT + filesystem doesn't have uid/gid on disk, so normal + check is too unflexible. With this option you can + relax it. + codepage=### -- Sets the codepage number for converting to shortname characters on FAT filesystem. By default, FAT_DEFAULT_CODEPAGE setting is used. diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index 54630095aa3c..c35ca9e40d4c 100644 --- a/Documentation/gpio.txt +++ b/Documentation/gpio.txt @@ -107,6 +107,16 @@ type of GPIO controller, and on one particular board 80-95 with an FPGA. The numbers need not be contiguous; either of those platforms could also use numbers 2000-2063 to identify GPIOs in a bank of I2C GPIO expanders. +If you want to initialize a structure with an invalid GPIO number, use +some negative number (perhaps "-EINVAL"); that will never be valid. To +test if a number could reference a GPIO, you may use this predicate: + + int gpio_is_valid(int number); + +A number that's not valid will be rejected by calls which may request +or free GPIOs (see below). Other numbers may also be rejected; for +example, a number might be valid but unused on a given board. + Whether a platform supports multiple GPIO controllers is currently a platform-specific implementation issue. diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt index be89f393274f..6877e7187113 100644 --- a/Documentation/kprobes.txt +++ b/Documentation/kprobes.txt @@ -37,6 +37,11 @@ registration function such as register_kprobe() specifies where the probe is to be inserted and what handler is to be called when the probe is hit. +There are also register_/unregister_*probes() functions for batch +registration/unregistration of a group of *probes. These functions +can speed up unregistration process when you have to unregister +a lot of probes at once. + The next three subsections explain how the different types of probes work. They explain certain things that you'll need to know in order to make the best use of Kprobes -- e.g., the @@ -190,10 +195,11 @@ code mapping. 4. API Reference The Kprobes API includes a "register" function and an "unregister" -function for each type of probe. Here are terse, mini-man-page -specifications for these functions and the associated probe handlers -that you'll write. See the files in the samples/kprobes/ sub-directory -for examples. +function for each type of probe. The API also includes "register_*probes" +and "unregister_*probes" functions for (un)registering arrays of probes. +Here are terse, mini-man-page specifications for these functions and +the associated probe handlers that you'll write. See the files in the +samples/kprobes/ sub-directory for examples. 4.1 register_kprobe @@ -319,6 +325,43 @@ void unregister_kretprobe(struct kretprobe *rp); Removes the specified probe. The unregister function can be called at any time after the probe has been registered. +NOTE: +If the functions find an incorrect probe (ex. an unregistered probe), +they clear the addr field of the probe. + +4.5 register_*probes + +#include <linux/kprobes.h> +int register_kprobes(struct kprobe **kps, int num); +int register_kretprobes(struct kretprobe **rps, int num); +int register_jprobes(struct jprobe **jps, int num); + +Registers each of the num probes in the specified array. If any +error occurs during registration, all probes in the array, up to +the bad probe, are safely unregistered before the register_*probes +function returns. +- kps/rps/jps: an array of pointers to *probe data structures +- num: the number of the array entries. + +NOTE: +You have to allocate(or define) an array of pointers and set all +of the array entries before using these functions. + +4.6 unregister_*probes + +#include <linux/kprobes.h> +void unregister_kprobes(struct kprobe **kps, int num); +void unregister_kretprobes(struct kretprobe **rps, int num); +void unregister_jprobes(struct jprobe **jps, int num); + +Removes each of the num probes in the specified array at once. + +NOTE: +If the functions find some incorrect probes (ex. unregistered +probes) in the specified array, they clear the addr field of those +incorrect probes. However, other probes in the array are +unregistered correctly. + 5. Kprobes Features and Limitations Kprobes allows multiple probes at the same address. Currently, diff --git a/Documentation/md.txt b/Documentation/md.txt index 396cdd982c26..a8b430627473 100644 --- a/Documentation/md.txt +++ b/Documentation/md.txt @@ -450,3 +450,9 @@ These currently include there are upper and lower limits (32768, 16). Default is 128. strip_cache_active (currently raid5 only) number of active entries in the stripe cache + preread_bypass_threshold (currently raid5 only) + number of times a stripe requiring preread will be bypassed by + a stripe that does not require preread. For fairness defaults + to 1. Setting this to 0 disables bypass accounting and + requires preread stripes to wait until all full-width stripe- + writes are complete. Valid values are 0 to stripe_cache_size. diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt index cf89e8cfd5bf..1d2a772506cf 100644 --- a/Documentation/powerpc/booting-without-of.txt +++ b/Documentation/powerpc/booting-without-of.txt @@ -2836,6 +2836,39 @@ platforms are moved over to use the flattened-device-tree model. big-endian; }; + r) Freescale Display Interface Unit + + The Freescale DIU is a LCD controller, with proper hardware, it can also + drive DVI monitors. + + Required properties: + - compatible : should be "fsl-diu". + - reg : should contain at least address and length of the DIU register + set. + - Interrupts : one DIU interrupt should be describe here. + + Example (MPC8610HPCD) + display@2c000 { + compatible = "fsl,diu"; + reg = <0x2c000 100>; + interrupts = <72 2>; + interrupt-parent = <&mpic>; + }; + + s) Freescale on board FPGA + + This is the memory-mapped registers for on board FPGA. + + Required properities: + - compatible : should be "fsl,fpga-pixis". + - reg : should contain the address and the lenght of the FPPGA register + set. + + Example (MPC8610HPCD) + board-control@e8000000 { + compatible = "fsl,fpga-pixis"; + reg = <0xe8000000 32>; + }; VII - Marvell Discovery mv64[345]6x System Controller chips =========================================================== diff --git a/Documentation/spi/spidev b/Documentation/spi/spidev index 5c8e1b988a08..ed2da5e5b28a 100644 --- a/Documentation/spi/spidev +++ b/Documentation/spi/spidev @@ -126,8 +126,8 @@ NOTES: FULL DUPLEX CHARACTER DEVICE API ================================ -See the sample program below for one example showing the use of the full -duplex programming interface. (Although it doesn't perform a full duplex +See the spidev_fdx.c sample program for one example showing the use of the +full duplex programming interface. (Although it doesn't perform a full duplex transfer.) The model is the same as that used in the kernel spi_sync() request; the individual transfers offer the same capabilities as are available to kernel drivers (except that it's not asynchronous). @@ -141,167 +141,3 @@ and bitrate for each transfer segment.) To make a full duplex request, provide both rx_buf and tx_buf for the same transfer. It's even OK if those are the same buffer. - - -SAMPLE PROGRAM -============== - --------------------------------- CUT HERE -#include <stdio.h> -#include <unistd.h> -#include <stdlib.h> -#include <fcntl.h> -#include <string.h> - -#include <sys/ioctl.h> -#include <sys/types.h> -#include <sys/stat.h> - -#include <linux/types.h> -#include <linux/spi/spidev.h> - - -static int verbose; - -static void do_read(int fd, int len) -{ - unsigned char buf[32], *bp; - int status; - - /* read at least 2 bytes, no more than 32 */ - if (len < 2) - len = 2; - else if (len > sizeof(buf)) - len = sizeof(buf); - memset(buf, 0, sizeof buf); - - status = read(fd, buf, len); - if (status < 0) { - perror("read"); - return; - } - if (status != len) { - fprintf(stderr, "short read\n"); - return; - } - - printf("read(%2d, %2d): %02x %02x,", len, status, - buf[0], buf[1]); - status -= 2; - bp = buf + 2; - while (status-- > 0) - printf(" %02x", *bp++); - printf("\n"); -} - -static void do_msg(int fd, int len) -{ - struct spi_ioc_transfer xfer[2]; - unsigned char buf[32], *bp; - int status; - - memset(xfer, 0, sizeof xfer); - memset(buf, 0, sizeof buf); - - if (len > sizeof buf) - len = sizeof buf; - - buf[0] = 0xaa; - xfer[0].tx_buf = (__u64) buf; - xfer[0].len = 1; - - xfer[1].rx_buf = (__u64) buf; - xfer[1].len = len; - - status = ioctl(fd, SPI_IOC_MESSAGE(2), xfer); - if (status < 0) { - perror("SPI_IOC_MESSAGE"); - return; - } - - printf("response(%2d, %2d): ", len, status); - for (bp = buf; len; len--) - printf(" %02x", *bp++); - printf("\n"); -} - -static void dumpstat(const char *name, int fd) -{ - __u8 mode, lsb, bits; - __u32 speed; - - if (ioctl(fd, SPI_IOC_RD_MODE, &mode) < 0) { - perror("SPI rd_mode"); - return; - } - if (ioctl(fd, SPI_IOC_RD_LSB_FIRST, &lsb) < 0) { - perror("SPI rd_lsb_fist"); - return; - } - if (ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits) < 0) { - perror("SPI bits_per_word"); - return; - } - if (ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed) < 0) { - perror("SPI max_speed_hz"); - return; - } - - printf("%s: spi mode %d, %d bits %sper word, %d Hz max\n", - name, mode, bits, lsb ? "(lsb first) " : "", speed); -} - -int main(int argc, char **argv) -{ - int c; - int readcount = 0; - int msglen = 0; - int fd; - const char *name; - - while ((c = getopt(argc, argv, "hm:r:v")) != EOF) { - switch (c) { - case 'm': - msglen = atoi(optarg); - if (msglen < 0) - goto usage; - continue; - case 'r': - readcount = atoi(optarg); - if (readcount < 0) - goto usage; - continue; - case 'v': - verbose++; - continue; - case 'h': - case '?': -usage: - fprintf(stderr, - "usage: %s [-h] [-m N] [-r N] /dev/spidevB.D\n", - argv[0]); - return 1; - } - } - - if ((optind + 1) != argc) - goto usage; - name = argv[optind]; - - fd = open(name, O_RDWR); - if (fd < 0) { - perror("open"); - return 1; - } - - dumpstat(name, fd); - - if (msglen) - do_msg(fd, msglen); - - if (readcount) - do_read(fd, readcount); - - close(fd); - return 0; -} diff --git a/Documentation/spi/spidev_fdx.c b/Documentation/spi/spidev_fdx.c new file mode 100644 index 000000000000..fc354f760384 --- /dev/null +++ b/Documentation/spi/spidev_fdx.c @@ -0,0 +1,158 @@ +#include <stdio.h> +#include <unistd.h> +#include <stdlib.h> +#include <fcntl.h> +#include <string.h> + +#include <sys/ioctl.h> +#include <sys/types.h> +#include <sys/stat.h> + +#include <linux/types.h> +#include <linux/spi/spidev.h> + + +static int verbose; + +static void do_read(int fd, int len) +{ + unsigned char buf[32], *bp; + int status; + + /* read at least 2 bytes, no more than 32 */ + if (len < 2) + len = 2; + else if (len > sizeof(buf)) + len = sizeof(buf); + memset(buf, 0, sizeof buf); + + status = read(fd, buf, len); + if (status < 0) { + perror("read"); + return; + } + if (status != len) { + fprintf(stderr, "short read\n"); + return; + } + + printf("read(%2d, %2d): %02x %02x,", len, status, + buf[0], buf[1]); + status -= 2; + bp = buf + 2; + while (status-- > 0) + printf(" %02x", *bp++); + printf("\n"); +} + +static void do_msg(int fd, int len) +{ + struct spi_ioc_transfer xfer[2]; + unsigned char buf[32], *bp; + int status; + + memset(xfer, 0, sizeof xfer); + memset(buf, 0, sizeof buf); + + if (len > sizeof buf) + len = sizeof buf; + + buf[0] = 0xaa; + xfer[0].tx_buf = (__u64) buf; + xfer[0].len = 1; + + xfer[1].rx_buf = (__u64) buf; + xfer[1].len = len; + + status = ioctl(fd, SPI_IOC_MESSAGE(2), xfer); + if (status < 0) { + perror("SPI_IOC_MESSAGE"); + return; + } + + printf("response(%2d, %2d): ", len, status); + for (bp = buf; len; len--) + printf(" %02x", *bp++); + printf("\n"); +} + +static void dumpstat(const char *name, int fd) +{ + __u8 mode, lsb, bits; + __u32 speed; + + if (ioctl(fd, SPI_IOC_RD_MODE, &mode) < 0) { + perror("SPI rd_mode"); + return; + } + if (ioctl(fd, SPI_IOC_RD_LSB_FIRST, &lsb) < 0) { + perror("SPI rd_lsb_fist"); + return; + } + if (ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits) < 0) { + perror("SPI bits_per_word"); + return; + } + if (ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed) < 0) { + perror("SPI max_speed_hz"); + return; + } + + printf("%s: spi mode %d, %d bits %sper word, %d Hz max\n", + name, mode, bits, lsb ? "(lsb first) " : "", speed); +} + +int main(int argc, char **argv) +{ + int c; + int readcount = 0; + int msglen = 0; + int fd; + const char *name; + + while ((c = getopt(argc, argv, "hm:r:v")) != EOF) { + switch (c) { + case 'm': + msglen = atoi(optarg); + if (msglen < 0) + goto usage; + continue; + case 'r': + readcount = atoi(optarg); + if (readcount < 0) + goto usage; + continue; + case 'v': + verbose++; + continue; + case 'h': + case '?': +usage: + fprintf(stderr, + "usage: %s [-h] [-m N] [-r N] /dev/spidevB.D\n", + argv[0]); + return 1; + } + } + + if ((optind + 1) != argc) + goto usage; + name = argv[optind]; + + fd = open(name, O_RDWR); + if (fd < 0) { + perror("open"); + return 1; + } + + dumpstat(name, fd); + + if (msglen) + do_msg(fd, msglen); + + if (readcount) + do_read(fd, readcount); + + close(fd); + return 0; +} diff --git a/Documentation/vm/numa_memory_policy.txt b/Documentation/vm/numa_memory_policy.txt index dd4986497996..bad16d3f6a47 100644 --- a/Documentation/vm/numa_memory_policy.txt +++ b/Documentation/vm/numa_memory_policy.txt @@ -135,77 +135,58 @@ most general to most specific: Components of Memory Policies - A Linux memory policy is a tuple consisting of a "mode" and an optional set - of nodes. The mode determine the behavior of the policy, while the - optional set of nodes can be viewed as the arguments to the behavior. + A Linux memory policy consists of a "mode", optional mode flags, and an + optional set of nodes. The mode determines the behavior of the policy, + the optional mode flags determine the behavior of the mode, and the + optional set of nodes can be viewed as the arguments to the policy + behavior. Internally, memory policies are implemented by a reference counted structure, struct mempolicy. Details of this structure will be discussed in context, below, as required to explain the behavior. - Note: in some functions AND in the struct mempolicy itself, the mode - is called "policy". However, to avoid confusion with the policy tuple, - this document will continue to use the term "mode". - Linux memory policy supports the following 4 behavioral modes: - Default Mode--MPOL_DEFAULT: The behavior specified by this mode is - context or scope dependent. - - As mentioned in the Policy Scope section above, during normal - system operation, the System Default Policy is hard coded to - contain the Default mode. - - In this context, default mode means "local" allocation--that is - attempt to allocate the page from the node associated with the cpu - where the fault occurs. If the "local" node has no memory, or the - node's memory can be exhausted [no free pages available], local - allocation will "fallback to"--attempt to allocate pages from-- - "nearby" nodes, in order of increasing "distance". + Default Mode--MPOL_DEFAULT: This mode is only used in the memory + policy APIs. Internally, MPOL_DEFAULT is converted to the NULL + memory policy in all policy scopes. Any existing non-default policy + will simply be removed when MPOL_DEFAULT is specified. As a result, + MPOL_DEFAULT means "fall back to the next most specific policy scope." - Implementation detail -- subject to change: "Fallback" uses - a per node list of sibling nodes--called zonelists--built at - boot time, or when nodes or memory are added or removed from - the system [memory hotplug]. These per node zonelist are - constructed with nodes in order of increasing distance based - on information provided by the platform firmware. + For example, a NULL or default task policy will fall back to the + system default policy. A NULL or default vma policy will fall + back to the task policy. - When a task/process policy or a shared policy contains the Default - mode, this also means "local allocation", as described above. + When specified in one of the memory policy APIs, the Default mode + does not use the optional set of nodes. - In the context of a VMA, Default mode means "fall back to task - policy"--which may or may not specify Default mode. Thus, Default - mode can not be counted on to mean local allocation when used - on a non-shared region of the address space. However, see - MPOL_PREFERRED below. - - The Default mode does not use the optional set of nodes. + It is an error for the set of nodes specified for this policy to + be non-empty. MPOL_BIND: This mode specifies that memory must come from the - set of nodes specified by the policy. - - The memory policy APIs do not specify an order in which the nodes - will be searched. However, unlike "local allocation", the Bind - policy does not consider the distance between the nodes. Rather, - allocations will fallback to the nodes specified by the policy in - order of numeric node id. Like everything in Linux, this is subject - to change. + set of nodes specified by the policy. Memory will be allocated from + the node in the set with sufficient free memory that is closest to + the node where the allocation takes place. MPOL_PREFERRED: This mode specifies that the allocation should be attempted from the single node specified in the policy. If that - allocation fails, the kernel will search other nodes, exactly as - it would for a local allocation that started at the preferred node - in increasing distance from the preferred node. "Local" allocation - policy can be viewed as a Preferred policy that starts at the node + allocation fails, the kernel will search other nodes, in order of + increasing distance from the preferred node based on information + provided by the platform firmware. containing the cpu where the allocation takes place. Internally, the Preferred policy uses a single node--the - preferred_node member of struct mempolicy. A "distinguished - value of this preferred_node, currently '-1', is interpreted - as "the node containing the cpu where the allocation takes - place"--local allocation. This is the way to specify - local allocation for a specific range of addresses--i.e. for - VMA policies. + preferred_node member of struct mempolicy. When the internal + mode flag MPOL_F_LOCAL is set, the preferred_node is ignored and + the policy is interpreted as local allocation. "Local" allocation + policy can be viewed as a Preferred policy that starts at the node + containing the cpu where the allocation takes place. + + It is possible for the user to specify that local allocation is + always preferred by passing an empty nodemask with this mode. + If an empty nodemask is passed, the policy cannot use the + MPOL_F_STATIC_NODES or MPOL_F_RELATIVE_NODES flags described + below. MPOL_INTERLEAVED: This mode specifies that page allocations be interleaved, on a page granularity, across the nodes specified in @@ -231,6 +212,154 @@ Components of Memory Policies the temporary interleaved system default policy works in this mode. + Linux memory policy supports the following optional mode flags: + + MPOL_F_STATIC_NODES: This flag specifies that the nodemask passed by + the user should not be remapped if the task or VMA's set of allowed + nodes changes after the memory policy has been defined. + + Without this flag, anytime a mempolicy is rebound because of a + change in the set of allowed nodes, the node (Preferred) or + nodemask (Bind, Interleave) is remapped to the new set of + allowed nodes. This may result in nodes being used that were + previously undesired. + + With this flag, if the user-specified nodes overlap with the + nodes allowed by the task's cpuset, then the memory policy is + applied to their intersection. If the two sets of nodes do not + overlap, the Default policy is used. + + For example, consider a task that is attached to a cpuset with + mems 1-3 that sets an Interleave policy over the same set. If + the cpuset's mems change to 3-5, the Interleave will now occur + over nodes 3, 4, and 5. With this flag, however, since only node + 3 is allowed from the user's nodemask, the "interleave" only + occurs over that node. If no nodes from the user's nodemask are + now allowed, the Default behavior is used. + + MPOL_F_STATIC_NODES cannot be combined with the + MPOL_F_RELATIVE_NODES flag. It also cannot be used for + MPOL_PREFERRED policies that were created with an empty nodemask + (local allocation). + + MPOL_F_RELATIVE_NODES: This flag specifies that the nodemask passed + by the user will be mapped relative to the set of the task or VMA's + set of allowed nodes. The kernel stores the user-passed nodemask, + and if the allowed nodes changes, then that original nodemask will + be remapped relative to the new set of allowed nodes. + + Without this flag (and without MPOL_F_STATIC_NODES), anytime a + mempolicy is rebound because of a change in the set of allowed + nodes, the node (Preferred) or nodemask (Bind, Interleave) is + remapped to the new set of allowed nodes. That remap may not + preserve the relative nature of the user's passed nodemask to its + set of allowed nodes upon successive rebinds: a nodemask of + 1,3,5 may be remapped to 7-9 and then to 1-3 if the set of + allowed nodes is restored to its original state. + + With this flag, the remap is done so that the node numbers from + the user's passed nodemask are relative to the set of allowed + nodes. In other words, if nodes 0, 2, and 4 are set in the user's + nodemask, the policy will be effected over the first (and in the + Bind or Interleave case, the third and fifth) nodes in the set of + allowed nodes. The nodemask passed by the user represents nodes + relative to task or VMA's set of allowed nodes. + + If the user's nodemask includes nodes that are outside the range + of the new set of allowed nodes (for example, node 5 is set in + the user's nodemask when the set of allowed nodes is only 0-3), + then the remap wraps around to the beginning of the nodemask and, + if not already set, sets the node in the mempolicy nodemask. + + For example, consider a task that is attached to a cpuset with + mems 2-5 that sets an Interleave policy over the same set with + MPOL_F_RELATIVE_NODES. If the cpuset's mems change to 3-7, the + interleave now occurs over nodes 3,5-6. If the cpuset's mems + then change to 0,2-3,5, then the interleave occurs over nodes + 0,3,5. + + Thanks to the consistent remapping, applications preparing + nodemasks to specify memory policies using this flag should + disregard their current, actual cpuset imposed memory placement + and prepare the nodemask as if they were always located on + memory nodes 0 to N-1, where N is the number of memory nodes the + policy is intended to manage. Let the kernel then remap to the + set of memory nodes allowed by the task's cpuset, as that may + change over time. + + MPOL_F_RELATIVE_NODES cannot be combined with the + MPOL_F_STATIC_NODES flag. It also cannot be used for + MPOL_PREFERRED policies that were created with an empty nodemask + (local allocation). + +MEMORY POLICY REFERENCE COUNTING + +To resolve use/free races, struct mempolicy contains an atomic reference +count field. Internal interfaces, mpol_get()/mpol_put() increment and +decrement this reference count, respectively. mpol_put() will only free +the structure back to the mempolicy kmem cache when the reference count +goes to zero. + +When a new memory policy is allocated, it's reference count is initialized +to '1', representing the reference held by the task that is installing the +new policy. When a pointer to a memory policy structure is stored in another +structure, another reference is added, as the task's reference will be dropped +on completion of the policy installation. + +During run-time "usage" of the policy, we attempt to minimize atomic operations +on the reference count, as this can lead to cache lines bouncing between cpus +and NUMA nodes. "Usage" here means one of the following: + +1) querying of the policy, either by the task itself [using the get_mempolicy() + API discussed below] or by another task using the /proc/<pid>/numa_maps + interface. + +2) examination of the policy to determine the policy mode and associated node + or node lists, if any, for page allocation. This is considered a "hot + path". Note that for MPOL_BIND, the "usage" extends across the entire + allocation process, which may sleep during page reclaimation, because the + BIND policy nodemask is used, by reference, to filter ineligible nodes. + +We can avoid taking an extra reference during the usages listed above as +follows: + +1) we never need to get/free the system default policy as this is never + changed nor freed, once the system is up and running. + +2) for querying the policy, we do not need to take an extra reference on the + target task's task policy nor vma policies because we always acquire the + task's mm's mmap_sem for read during the query. The set_mempolicy() and + mbind() APIs [see below] always acquire the mmap_sem for write when + installing or replacing task or vma policies. Thus, there is no possibility + of a task or thread freeing a policy while another task or thread is + querying it. + +3) Page allocation usage of task or vma policy occurs in the fault path where + we hold them mmap_sem for read. Again, because replacing the task or vma + policy requires that the mmap_sem be held for write, the policy can't be + freed out from under us while we're using it for page allocation. + +4) Shared policies require special consideration. One task can replace a + shared memory policy while another task, with a distinct mmap_sem, is + querying or allocating a page based on the policy. To resolve this + potential race, the shared policy infrastructure adds an extra reference + to the shared policy during lookup while holding a spin lock on the shared + policy management structure. This requires that we drop this extra + reference when we're finished "using" the policy. We must drop the + extra reference on shared policies in the same query/allocation paths + used for non-shared policies. For this reason, shared policies are marked + as such, and the extra reference is dropped "conditionally"--i.e., only + for shared policies. + + Because of this extra reference counting, and because we must lookup + shared policies in a tree structure under spinlock, shared policies are + more expensive to use in the page allocation path. This is expecially + true for shared policies on shared memory regions shared by tasks running + on different NUMA nodes. This extra overhead can be avoided by always + falling back to task or system default policy for shared memory regions, + or by prefaulting the entire shared memory region into memory and locking + it down. However, this might not be appropriate for all applications. + MEMORY POLICY APIs Linux supports 3 system calls for controlling memory policy. These APIS @@ -251,7 +380,9 @@ Set [Task] Memory Policy: Set's the calling task's "task/process memory policy" to mode specified by the 'mode' argument and the set of nodes defined by 'nmask'. 'nmask' points to a bit mask of node ids containing - at least 'maxnode' ids. + at least 'maxnode' ids. Optional mode flags may be passed by + combining the 'mode' argument with the flag (for example: + MPOL_INTERLEAVE | MPOL_F_STATIC_NODES). See the set_mempolicy(2) man page for more details @@ -303,29 +434,19 @@ MEMORY POLICIES AND CPUSETS Memory policies work within cpusets as described above. For memory policies that require a node or set of nodes, the nodes are restricted to the set of nodes whose memories are allowed by the cpuset constraints. If the nodemask -specified for the policy contains nodes that are not allowed by the cpuset, or -the intersection of the set of nodes specified for the policy and the set of -nodes with memory is the empty set, the policy is considered invalid -and cannot be installed. - -The interaction of memory policies and cpusets can be problematic for a -couple of reasons: - -1) the memory policy APIs take physical node id's as arguments. As mentioned - above, it is illegal to specify nodes that are not allowed in the cpuset. - The application must query the allowed nodes using the get_mempolicy() - API with the MPOL_F_MEMS_ALLOWED flag to determine the allowed nodes and - restrict itself to those nodes. However, the resources available to a - cpuset can be changed by the system administrator, or a workload manager - application, at any time. So, a task may still get errors attempting to - specify policy nodes, and must query the allowed memories again. - -2) when tasks in two cpusets share access to a memory region, such as shared - memory segments created by shmget() of mmap() with the MAP_ANONYMOUS and - MAP_SHARED flags, and any of the tasks install shared policy on the region, - only nodes whose memories are allowed in both cpusets may be used in the - policies. Obtaining this information requires "stepping outside" the - memory policy APIs to use the cpuset information and requires that one - know in what cpusets other task might be attaching to the shared region. - Furthermore, if the cpusets' allowed memory sets are disjoint, "local" - allocation is the only valid policy. +specified for the policy contains nodes that are not allowed by the cpuset and +MPOL_F_RELATIVE_NODES is not used, the intersection of the set of nodes +specified for the policy and the set of nodes with memory is used. If the +result is the empty set, the policy is considered invalid and cannot be +installed. If MPOL_F_RELATIVE_NODES is used, the policy's nodes are mapped +onto and folded into the task's set of allowed nodes as previously described. + +The interaction of memory policies and cpusets can be problematic when tasks +in two cpusets share access to a memory region, such as shared memory segments +created by shmget() of mmap() with the MAP_ANONYMOUS and MAP_SHARED flags, and +any of the tasks install shared policy on the region, only nodes whose +memories are allowed in both cpusets may be used in the policies. Obtaining +this information requires "stepping outside" the memory policy APIs to use the +cpuset information and requires that one know in what cpusets other task might +be attaching to the shared region. Furthermore, if the cpusets' allowed +memory sets are disjoint, "local" allocation is the only valid policy. |