diff options
Diffstat (limited to 'doc/develop')
| -rw-r--r-- | doc/develop/distro.rst | 4 | ||||
| -rw-r--r-- | doc/develop/index.rst | 2 | ||||
| -rw-r--r-- | doc/develop/init.rst | 93 | ||||
| -rw-r--r-- | doc/develop/logging.rst | 2 | ||||
| -rw-r--r-- | doc/develop/memory.rst | 49 | ||||
| -rw-r--r-- | doc/develop/qconfig.rst | 2 | ||||
| -rw-r--r-- | doc/develop/spl.rst | 83 | ||||
| -rw-r--r-- | doc/develop/tests_sandbox.rst | 2 | ||||
| -rw-r--r-- | doc/develop/tests_writing.rst | 6 | ||||
| -rw-r--r-- | doc/develop/uefi/uefi.rst | 2 |
10 files changed, 197 insertions, 48 deletions
diff --git a/doc/develop/distro.rst b/doc/develop/distro.rst index 9e715b23ebb..637bc27fc2d 100644 --- a/doc/develop/distro.rst +++ b/doc/develop/distro.rst @@ -189,7 +189,7 @@ TO BE UPDATED: In your board configuration file, include the following:: - #ifndef CONFIG_SPL_BUILD + #ifndef CONFIG_XPL_BUILD #include <config_distro_bootcmd.h> #endif @@ -316,7 +316,7 @@ that it supports the correct set of possible boot device types. To provide this configuration, simply define macro BOOT_TARGET_DEVICES prior to including <config_distro_bootcmd.h>. For example:: - #ifndef CONFIG_SPL_BUILD + #ifndef CONFIG_XPL_BUILD #define BOOT_TARGET_DEVICES(func) \ func(MMC, mmc, 1) \ func(MMC, mmc, 0) \ diff --git a/doc/develop/index.rst b/doc/develop/index.rst index 0d0e60ab56c..c23192c2770 100644 --- a/doc/develop/index.rst +++ b/doc/develop/index.rst @@ -13,6 +13,7 @@ General codingstyle designprinciples docstyle + memory patman process release_cycle @@ -38,6 +39,7 @@ Implementation distro driver-model/index environment + init expo cedit event diff --git a/doc/develop/init.rst b/doc/develop/init.rst new file mode 100644 index 00000000000..ce985781bb4 --- /dev/null +++ b/doc/develop/init.rst @@ -0,0 +1,93 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +Board Initialisation Flow +------------------------- + +This is the intended start-up flow for boards. This should apply for both +xPL and U-Boot proper (i.e. they both follow the same rules). + +Note: "xPL" stands for "any Program Loader", including SPL (Secondary +Program Loader), TPL (Tertiary Program Loader) and VPL (Verifying Program +Loader). The boot sequence is TPL->VPL->SPL->U-Boot proper + +At present, xPL mostly uses a separate code path, but the function names +and roles of each function are the same. Some boards or architectures +may not conform to this. At least most ARM boards which use +CONFIG_xPL_FRAMEWORK conform to this. + +Execution typically starts with an architecture-specific (and possibly +CPU-specific) start.S file, such as: + +- arch/arm/cpu/armv7/start.S +- arch/powerpc/cpu/mpc83xx/start.S +- arch/mips/cpu/start.S + +and so on. From there, three functions are called; the purpose and +limitations of each of these functions are described below. + +lowlevel_init() +~~~~~~~~~~~~~~~ + +- purpose: essential init to permit execution to reach board_init_f() +- no global_data or BSS +- there is no stack (ARMv7 may have one but it will soon be removed) +- must not set up SDRAM or use console +- must only do the bare minimum to allow execution to continue to + board_init_f() +- this is almost never needed +- return normally from this function + +board_init_f() +~~~~~~~~~~~~~~ + +- purpose: set up the machine ready for running board_init_r(): + i.e. SDRAM and serial UART +- global_data is available +- stack is in SRAM +- BSS is not available, so you cannot use global/static variables, + only stack variables and global_data + +Non-xPL-specific notes: + + - dram_init() is called to set up DRAM. If already done in xPL this + can do nothing + +xPL-specific notes: + + - you can override the entire board_init_f() function with your own + version as needed. + - preloader_console_init() can be called here in extremis + - should set up SDRAM, and anything needed to make the UART work + - there is no need to clear BSS, it will be done by crt0.S + - for specific scenarios on certain architectures an early BSS *can* + be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing + of BSS prior to entering board_init_f()) but doing so is discouraged. + Instead it is strongly recommended to architect any code changes + or additions such to not depend on the availability of BSS during + board_init_f() as indicated in other sections of this README to + maintain compatibility and consistency across the entire code base. + - must return normally from this function (don't call board_init_r() + directly) + +Here the BSS is cleared. For xPL, if CONFIG_xPL_STACK_R is defined, then at +this point the stack and global_data are relocated to below +CONFIG_xPL_STACK_R_ADDR. For non-xPL, U-Boot is relocated to run at the top of +memory. + +board_init_r() +~~~~~~~~~~~~~~ + + - purpose: main execution, common code + - global_data is available + - SDRAM is available + - BSS is available, all static/global variables can be used + - execution eventually continues to main_loop() + +Non-xPL-specific notes: + + - U-Boot is relocated to the top of memory and is now running from + there. + +xPL-specific notes: + + - stack is optionally in SDRAM, if CONFIG_xPL_STACK_R is defined diff --git a/doc/develop/logging.rst b/doc/develop/logging.rst index 704a6bf1d84..d7a40c94bf0 100644 --- a/doc/develop/logging.rst +++ b/doc/develop/logging.rst @@ -292,7 +292,7 @@ Convert debug() statements in the code to log() statements Convert error() statements in the code to log() statements -Figure out what to do with BUG(), BUG_ON() and warn_non_spl() +Figure out what to do with BUG(), BUG_ON() and warn_non_xpl() Add a way to browse log records diff --git a/doc/develop/memory.rst b/doc/develop/memory.rst new file mode 100644 index 00000000000..e9e65ba4c6c --- /dev/null +++ b/doc/develop/memory.rst @@ -0,0 +1,49 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +Memory Management +----------------- + +.. note:: + + This information is outdated and needs to be updated. + +U-Boot runs in system state and uses physical addresses, i.e. the +MMU is not used either for address mapping nor for memory protection. + +The available memory is mapped to fixed addresses using the +memory-controller. In this process, a contiguous block is formed for each +memory type (Flash, SDRAM, SRAM), even when it consists of several +physical-memory banks. + +U-Boot is installed in XIP flash memory, or may be loaded into a lower region of +RAM by a secondary program loader (SPL). After +booting and sizing and initialising DRAM, the code relocates itself +to the upper end of DRAM. Immediately below the U-Boot code some +memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN +configuration setting]. Below that, a structure with global Board-Info +data is placed, followed by the stack (growing downward). + +Additionally, some exception handler code may be copied to the low 8 kB +of DRAM (0x00000000 ... 0x00001fff). + +So a typical memory configuration with 16 MB of DRAM could look like +this:: + + 0x0000 0000 Exception Vector code + : + 0x0000 1fff + 0x0000 2000 Free for Application Use + : + : + + : + : + 0x00fb ff20 Monitor Stack (Growing downward) + 0x00fb ffac Board Info Data and permanent copy of global data + 0x00fc 0000 Malloc Arena + : + 0x00fd ffff + 0x00fe 0000 RAM Copy of Monitor Code + ... eventually: LCD or video framebuffer + ... eventually: pRAM (Protected RAM - unchanged by reset) + 0x00ff ffff [End of RAM] diff --git a/doc/develop/qconfig.rst b/doc/develop/qconfig.rst index 123779eab17..a18f32470ca 100644 --- a/doc/develop/qconfig.rst +++ b/doc/develop/qconfig.rst @@ -226,7 +226,7 @@ Available options Look for moved config options in spl/include/autoconf.mk instead of include/autoconf.mk. This is useful for moving options for SPL build because SPL related options (mostly prefixed with CONFIG_SPL\_) are - sometimes blocked by CONFIG_SPL_BUILD ifdef conditionals. + sometimes blocked by CONFIG_XPL_BUILD ifdef conditionals. -j, --jobs Specify the number of threads to run simultaneously. If not specified, diff --git a/doc/develop/spl.rst b/doc/develop/spl.rst index 4bb48e6b7b3..aa6d28fa333 100644 --- a/doc/develop/spl.rst +++ b/doc/develop/spl.rst @@ -1,11 +1,12 @@ -Generic SPL framework +Generic xPL framework ===================== Overview -------- -To unify all existing implementations for a secondary program loader (SPL) -and to allow simply adding of new implementations this generic SPL framework +To unify all existing implementations for secondary/tertiary program loaders +(generically called xPL) +and to allow simply adding of new implementations this generic xPL framework has been created. With this framework almost all source files for a board can be reused. No code duplication or symlinking is necessary anymore. @@ -13,36 +14,39 @@ can be reused. No code duplication or symlinking is necessary anymore. How it works ------------ -The object files for SPL are built separately and placed in the "spl" directory. -The final binaries which are generated are u-boot-spl, u-boot-spl.bin and -u-boot-spl.map. +The object files for xPL are built separately and placed in a subdirectory +("spl", "tpl" or "vpl"). +The final binaries which are generated for SPL are u-boot-spl, u-boot-spl.bin +and u-boot-spl.map -A config option named CONFIG_SPL_BUILD is enabled by Kconfig for SPL. -Source files can therefore be compiled for SPL with different settings. +A config option named CONFIG_XPL_BUILD is enabled by Kconfig for xPL builds. +Source files can therefore be compiled for xPL with different settings. For example:: - ifeq ($(CONFIG_SPL_BUILD),y) + ifeq ($(CONFIG_XPL_BUILD),y) obj-y += board_spl.o else obj-y += board.o endif - obj-$(CONFIG_SPL_BUILD) += foo.o + obj-$(CONFIG_XPL_BUILD) += foo.o - #ifdef CONFIG_SPL_BUILD + if (IS_ENABLED(CONFIG_XPL_BUILD)) foo(); - #endif + if (xpl_phase() == PHASE_TPL) + bar(); -The building of SPL images can be enabled by CONFIG_SPL option in Kconfig. +The building of xPL images can be enabled by CONFIG_SPL (etc.) options in +Kconfig. -Because SPL images normally have a different text base, one has to be -configured by defining CONFIG_SPL_TEXT_BASE. The linker script has to be -defined with CONFIG_SPL_LDSCRIPT. +Because xPL images normally have a different text base, one has to be +configured by defining CONFIG_xPL_TEXT_BASE. The linker script has to be +defined with CONFIG_xPL_LDSCRIPT. -To support generic U-Boot libraries and drivers in the SPL binary one can -optionally define CONFIG_SPL_XXX_SUPPORT. Currently following options +To support generic U-Boot libraries and drivers in the xPL binary one can +optionally define CONFIG_xPL_XXX_SUPPORT. Currently following options are supported: CONFIG_SPL_LIBCOMMON_SUPPORT (common/libcommon.o) @@ -75,7 +79,7 @@ CONFIG_SPL_DM_GPIO (drivers/gpio/gpio-uclass.o) CONFIG_SPL_BMP (drivers/video/bmp.o) CONFIG_SPL_BLOBLIST (common/bloblist.o) -Adding SPL-specific code +Adding xPL-specific code ------------------------ To check whether a feature is enabled, use CONFIG_IS_ENABLED():: @@ -90,7 +94,7 @@ U-Boot Boot Phases ------------------ U-Boot goes through the following boot phases where TPL, VPL, SPL are optional. -While many boards use SPL, less use TPL. +While many boards use SPL, fewer use TPL. TPL Very early init, as tiny as possible. This loads SPL (or VPL if enabled). @@ -117,7 +121,7 @@ Further usages of U-Boot SPL comprise: Checking the boot phase ----------------------- -Use `spl_phase()` to find the current U-Boot phase, e.g. `PHASE_SPL`. You can +Use `xpl_phase()` to find the current U-Boot phase, e.g. `PHASE_SPL`. You can also find the previous and next phase and get the phase name. @@ -177,29 +181,30 @@ files instead introduces another set of headaches. These warnings are not usually important to understanding the flow, however. -Reserving memory in SPL +Reserving memory in xPL ----------------------- -If memory needs to be reserved in RAM during SPL stage with the requirement that -the SPL reserved memory remains preserved across further boot stages too +If memory needs to be reserved in RAM during an xPL phase with the requirement +that the xPL reserved memory remains preserved across further boot phases too then it needs to be reserved mandatorily starting from end of RAM. This is to -ensure that further stages can simply skip this region before carrying out +ensure that further phases can simply skip this region before carrying out further reservations or updating the relocation address. -Also out of these regions which are to be preserved across further stages of +Also out of these regions which are to be preserved across further phases of boot, video framebuffer memory region must be reserved first starting from -end of RAM for which helper function spl_reserve_video_from_ram_top is provided -which makes sure that video memory is placed at top of reservation area with +end of RAM for which the helper function spl_reserve_video_from_ram_top() is +provided +which makes sure that video memory is placed at the top of reservation area with further reservations below it. -The corresponding information of reservation for those regions can be passed to -further boot stages using a bloblist. For e.g. the information for -framebuffer area reserved by SPL can be passed onto U-boot using -BLOBLISTT_U_BOOT_VIDEO. - -The further boot stages need to parse each of the bloblist passed from SPL stage -starting from video bloblist and skip this whole SPL reserved memory area from -end of RAM as per the bloblists received, before carrying out further -reservations or updating the relocation address. For e.g, U-boot proper uses -function "setup_relocaddr_from_bloblist" to parse the bloblists passed from -previous stage and skip the memory reserved from previous stage accordingly. +The reservation information for these regions can be passed to the +further boot phases using a bloblist. For e.g. the information for the +framebuffer area reserved by xPL can be passed onto U-Boot using +BLOBLISTT_U_BOOT_VIDEO + +The further boot phases need to parse each of the blobs passed from xPL phase +starting from video bloblist and skip this whole xPL reserved-memory area from +end of RAM as per the blobs received, before carrying out further +reservations or updating the relocation address. For e.g, U-Boot proper uses +function setup_relocaddr_from_bloblist() to parse the bloblist passed from +previous phase and skip the memory reserved from previous phase accordingly. diff --git a/doc/develop/tests_sandbox.rst b/doc/develop/tests_sandbox.rst index 72923070150..0630180bc55 100644 --- a/doc/develop/tests_sandbox.rst +++ b/doc/develop/tests_sandbox.rst @@ -278,7 +278,7 @@ Whatever sandbox build is used, which tests are present is determined by which source files are built. For sandbox_spl, the of_platdata tests are built because of the build rule in test/dm/Makefile:: - ifeq ($(CONFIG_SPL_BUILD),y) + ifeq ($(CONFIG_XPL_BUILD),y) obj-$(CONFIG_SPL_OF_PLATDATA) += of_platdata.o else ...other tests for non-spl diff --git a/doc/develop/tests_writing.rst b/doc/develop/tests_writing.rst index a328ebfef33..54efb7e1b04 100644 --- a/doc/develop/tests_writing.rst +++ b/doc/develop/tests_writing.rst @@ -321,15 +321,15 @@ to control that. Finally, add the test to the build by adding to the Makefile in the same directory:: - obj-$(CONFIG_$(SPL_)CMDLINE) += wibble.o + obj-$(CONFIG_$(XPL_)CMDLINE) += wibble.o Note that CMDLINE is never enabled in SPL, so this test will only be present in U-Boot proper. See below for how to do SPL tests. As before, you can add an extra Kconfig check if needed:: - ifneq ($(CONFIG_$(SPL_)WIBBLE),) - obj-$(CONFIG_$(SPL_)CMDLINE) += wibble.o + ifneq ($(CONFIG_$(XPL_)WIBBLE),) + obj-$(CONFIG_$(XPL_)CMDLINE) += wibble.o endif diff --git a/doc/develop/uefi/uefi.rst b/doc/develop/uefi/uefi.rst index 94482758573..0760ca91d4f 100644 --- a/doc/develop/uefi/uefi.rst +++ b/doc/develop/uefi/uefi.rst @@ -720,7 +720,7 @@ Executing the built in hello world application A hello world UEFI application can be built with:: - CONFIG_CMD_BOOTEFI_HELLO_COMPILE=y + CONFIG_BOOTEFI_HELLO_COMPILE=y It can be embedded into the U-Boot binary with:: |