[PATCH] Real-Time Preemption, fixed kexec kernel relocation oops

From: Luca Falavigna
Date: Mon Aug 29 2005 - 12:27:00 EST


This patch, built against kernel version 2.6.13-rc7 (and not against -RT tree
patch, sorry), fixes a few local_irq_disable() calls which leads to an oops
during kernel relocation in kexec subsystem. Currently, only i386 implementation
of kexec is fixed.

Anyway, this patch does not fix a strange behaviour when using kexec with a -RT
kernel. Here is dmesg output:

Uncompressing Linux... OK, booting the kernel.
Unknown interrupt or fault at EIP 00000203 00000060 c011dfe3
Linux version 2.6.13-rc7-rt1 (root@sauron) (gcc version 3.3.4 (Debian
1:3.3.4-13)) #2 Fri Aug 26 16:55:12 UTC 2005
[...]
hda: lost interrupt
hda: lost interrupt
hda: lost interrupt
[...]

System is very slow and there are tons of "lost interrupt" messages.



Signed-off-by: Luca Falavigna <dktrkranz@xxxxxxxxx>

--- ./arch/i386/kernel/machine_kexec.c.orig 2005-08-28 22:03:52.000000000 +0000
+++ ./arch/i386/kernel/machine_kexec.c 2005-08-28 22:05:28.000000000 +0000
@@ -187,7 +187,7 @@ NORET_TYPE void machine_kexec(struct kim
relocate_new_kernel_t rnk;

/* Interrupts aren't acceptable while we reboot */
- local_irq_disable();
+ raw_local_irq_disable();

/* Compute some offsets */
reboot_code_buffer = page_to_pfn(image->control_code_page)
--- ./arch/i386/kernel/crash.c.orig 2005-08-28 22:04:08.000000000 +0000
+++ ./arch/i386/kernel/crash.c 2005-08-28 22:04:55.000000000 +0000
@@ -143,7 +143,7 @@ static int crash_nmi_callback(struct pt_
*/
if (cpu == crashing_cpu)
return 1;
- local_irq_disable();
+ raw_local_irq_disable();

if (!user_mode(regs)) {
crash_setup_regs(&fixed_regs, regs);
@@ -210,7 +210,7 @@ void machine_crash_shutdown(struct pt_re
* an SMP system.
*/
/* The kernel is broken so disable interrupts */
- local_irq_disable();
+ raw_local_irq_disable();

/* Make a note of crashing cpu. Will be used in NMI callback.*/
crashing_cpu = smp_processor_id();




Regards,
--
Luca


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