linux-toradex.git/init/main.c, branch v2.6.23.12

fix maxcpus=1 oops in show_stat()

2007-08-31T04:54:31+00:00

Alexey Dobriyan reports that maxcpus=1 is still broken in 2.6.23-rc4:
if CONFIG_HOTPLUG_CPU is not set, x86_64 bootup oopses in show_stat() -
for_each_possible_cpu accesses a per-cpu area which was never set up.

Alexey identified commit 61ec7567db103d537329b0db9a887db570431ff4
(ACPI: boot correctly with "nosmp" or "maxcpus=0") as the origin;
but it's not really to blame, just exposes a bug in 2.6.23-rc1's commit
8b3b295502444340dd0701855ac422fbf32e161d (Especially when !CONFIG_HOTPLUG_CPU,
avoid needlessy allocating resources for CPUs that can never become available).

rc1's test for max_cpus < 2 in start_kernel() wasn't working because
max_cpus was still NR_CPUS at that point: until rc4 moved the maxcpus
parsing earlier.  Now it sets cpu_possible_map to 1 before allocating
all possible per-cpu areas; then smp_init() expands cpu_possible_map
to cpu_present_map (0xf in my case) later on.

rc1's commit has good intentions, but expects cpu_present_map to be
limited by maxcpus, which is only the case on i386.  cpus_and(possible,
possible,present) might be good, but needs an audit of cpu_present_map
uses - there may well be assumptions that any cpu present is possible.

So stay safe for now and just revert those #ifndef CONFIG_HOTPLUG_CPU
optimizations in rc1's commit.

Signed-off-by: Hugh Dickins 
Cc: Alexey Dobriyan 
Cc: Len Brown 
Cc: Andrew Morton 
Cc: Jan Beulich 
Signed-off-by: Linus Torvalds

fix maxcpus=N parsing

2007-08-27T17:27:48+00:00

Commit 61ec7567db103d537329b0db9a887db570431ff4 ('ACPI: boot correctly
with "nosmp" or "maxcpus=0"') broke 'maxcpus=' handling on x86[-64].

maxcpus=N is now having no effect on x86_64, and freezing bootup on i386
(because of inconsistency with the separate maxcpus parsing down in
arch/i386, I guess).  That's because early_param parsing is a little
different from __setup parsing, and needs the "=" omitted: then it seems
to work as the original commit intended (no mention of IO-APIC in
/proc/interrupts when maxcpus=0).

Signed-off-by: Hugh Dickins 
Cc: Andrew Morton 
Cc: Len Brown 
Cc: Andi Kleen 
Cc: Rusty Russell 
Signed-off-by: Linus Torvalds

ACPI: boot correctly with "nosmp" or "maxcpus=0"

2007-08-21T04:33:35+00:00

In MPS mode, "nosmp" and "maxcpus=0" boot a UP kernel with IOAPIC disabled.
However, in ACPI mode, these parameters didn't completely disable
the IO APIC initialization code and boot failed.

init/main.c:
	Disable the IO_APIC if "nosmp" or "maxcpus=0"
	undefine disable_ioapic_setup() when it doesn't apply.

i386:
	delete ioapic_setup(), it was a duplicate of parse_noapic()
	delete undefinition of disable_ioapic_setup()

x86_64:
	rename disable_ioapic_setup() to parse_noapic() to match i386
	define disable_ioapic_setup() in header to match i386

http://bugzilla.kernel.org/show_bug.cgi?id=1641

Acked-by: Andi Kleen 
Signed-off-by: Len Brown

adjust nosmp handling

2007-07-16T16:05:47+00:00

Especially when !CONFIG_HOTPLUG_CPU, avoid needlessy allocating resources for
CPUs that can never become available.

Signed-off-by: Jan Beulich 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Allow softlockup to be runtime disabled

2007-07-16T16:05:47+00:00

It's useful sometimes to disable the softlockup checker at boottime.
Especially if it triggers during a distro install.

Signed-off-by: Dave Jones 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

serial: convert early_uart to earlycon for 8250

2007-07-16T16:05:35+00:00

Beacuse SERIAL_PORT_DFNS is removed from include/asm-i386/serial.h and
include/asm-x86_64/serial.h.  the serial8250_ports need to be probed late in
serial initializing stage.  the console_init=>serial8250_console_init=>
register_console=>serial8250_console_setup will return -ENDEV, and console
ttyS0 can not be enabled at that time.  need to wait till uart_add_one_port in
drivers/serial/serial_core.c to call register_console to get console ttyS0.
that is too late.

Make early_uart to use early_param, so uart console can be used earlier.  Make
it to be bootconsole with CON_BOOT flag, so can use console handover feature.
and it will switch to corresponding normal serial console automatically.

new command line will be:
	console=uart8250,io,0x3f8,9600n8
	console=uart8250,mmio,0xff5e0000,115200n8
or
	earlycon=uart8250,io,0x3f8,9600n8
	earlycon=uart8250,mmio,0xff5e0000,115200n8

it will print in very early stage:
	Early serial console at I/O port 0x3f8 (options '9600n8')
	console [uart0] enabled
later for console it will print:
	console handover: boot [uart0] -> real [ttyS0]

Signed-off-by: 
Cc: Andi Kleen 
Cc: Bjorn Helgaas 
Cc: Russell King 
Cc: Gerd Hoffmann 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sched: add init_idle_bootup_task()

2007-07-09T16:51:58+00:00

add the init_idle_bootup_task() callback to the bootup thread,
unused at the moment. (CFS will use it to switch the scheduling
class of the boot thread to the idle class)

Signed-off-by: Ingo Molnar

init/main: use __init_refok to fix section mismatch

2007-05-19T07:11:58+00:00

Kill a special case in modpost by introducing the
__init_refok marker.

Signed-off-by: Sam Ravnborg

Explicitly set pgid and sid of init process

2007-05-11T15:29:35+00:00

Explicitly set pgid and sid of init process to 1.

Signed-off-by: Sukadev Bhattiprolu 
Cc: Cedric Le Goater 
Cc: Dave Hansen 
Cc: Serge Hallyn 
Cc: Eric Biederman 
Cc: Herbert Poetzl 
Cc: 
Acked-by: Eric W. Biederman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kthread: don't depend on work queues

2007-05-09T19:30:53+00:00

Currently there is a circular reference between work queue initialization
and kthread initialization.  This prevents the kthread infrastructure from
initializing until after work queues have been initialized.

We want the properties of tasks created with kthread_create to be as close
as possible to the init_task and to not be contaminated by user processes.
The later we start our kthreadd that creates these tasks the harder it is
to avoid contamination from user processes and the more of a mess we have
to clean up because the defaults have changed on us.

So this patch modifies the kthread support to not use work queues but to
instead use a simple list of structures, and to have kthreadd start from
init_task immediately after our kernel thread that execs /sbin/init.

By being a true child of init_task we only have to change those process
settings that we want to have different from init_task, such as our process
name, the cpus that are allowed, blocking all signals and setting SIGCHLD
to SIG_IGN so that all of our children are reaped automatically.

By being a true child of init_task we also naturally get our ppid set to 0
and do not wind up as a child of PID == 1.  Ensuring that tasks generated
by kthread_create will not slow down the functioning of the wait family of
functions.

[akpm@linux-foundation.org: use interruptible sleeps]
Signed-off-by: Eric W. Biederman 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds