Hi All
In case of a crash we would like to save the kernel log and retrieve it in
the next boot.
There are already several suggestions on how to do it on this and other
lists.
(Kernel crashing and log buffers: Robin Getz)
Unfortunately we don't have extra SRAM to use for it. We need to do it in
the 'normal' RAM.
ARCH=ARM
What we did:
- modify kernel/printk.c: use
__attribute__((__section__(".bss.kringbuf"... to put the log related stuf
into a separate section
- modify the linker script to link .bss.kringbuf at the start of the .bss
section
- modify arch/arm/kernel/head-common.S to exclude the new section from
being nulled (if it was a watchdog restart)
- modify kernel/printk.c to use cach_flush after prink
- make sure the bootloader does not overwrite that memory
This seems to work.
After a crash we get the messages from the new boot and the last crash.
It seems that the decompress code is using memory at the end of the kernel
and destroys the log. So we have to use the bootloader to decompress the
image into RAM.
Before digging any deeper I would like to know if someone as a better
(more general) idea.
Regards, Martin
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