This patch resolves a kexec boot failure that can occur because
no ATAGs are passed in to the kexec'd kernel. Currently the
newly-kexec'd kernel may fail if it requires specific ATAGs, or
it may fail because the fixed memory location at which it expects
to find the ATAGs may contain random data instead of ATAGs.
The patch ensures that any ATAGs passed to the current kernel
at boot time are copied to a static buffer, and are copied back
when kexec copies the new kernel into place. Thus the new
kernel sees the same ATAGs from kexec and the boot loader.
The boot parameters are copied without regard to type, content,
or length -- this patch's scope is limited soley to saving and
restoring a fixed-size block of memory containing the kernel's
boot parameters. Additional functionality to examine, alter, or
replace the ATAGs (using kexec, for example) can be implemented
by manipulating the static buffer containing the preserved ATAGs.
Note: the size of the buffer (1.5KB) is selected to comfortably
hold one of each ATAG type, including a maximum-length command
line and the maximum number of ATAG_MEM structures currently
supported by the kernel. Should an ATAG list exceed that limit,
the list will be silently truncated to that limit (to do other-
wise at that point in the boot process would make a simple
problem exceedingly complicated).
[Note: this is the same patch as 4579, modified to accomodate
the ATAG changes introduced in 2.6.23]
Signed-off-by: Mike Westerhof <mwester at dls.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Currently the size of the per-cpu region reserved to save crash notes is
set by the per-architecture value MAX_NOTE_BYTES. Which in turn is
currently set to 1024 on all supported architectures.
While testing ia64 I recently discovered that this value is in fact too
small. The particular setup I was using actually needs 1172 bytes. This
lead to very tedious failure mode where the tail of one elf note would
overwrite the head of another if they ended up being alocated sequentially
by kmalloc, which was often the case.
It seems to me that a far better approach is to caclculate the size that
the area needs to be. This patch does just that.
If a simpler stop-gap patch for ia64 to be squeezed into 2.6.21(.X) is
needed then this should be as easy as making MAX_NOTE_BYTES larger in
arch/asm-ia64/kexec.h. Perhaps 2048 would be a good choice. However, I
think that the approach in this patch is a much more robust idea.
Acked-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add kexec support to ARM.
Improvements like commandline handling could be made but this patch gives
basic functional support. It uses the next available syscall number, 347.
Once the syscall number is known, userspace support will be
finalised/submitted to kexec-tools, various patches already exist.
Originally based on a patch by Maxim Syrchin but updated and forward
ported by various people.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
