[kexec-tools][PATCH v2] zImage-arm: bugfix: kernel offset must be 0x8000
horms at verge.net.au
Sat May 10 16:48:37 PDT 2014
On Tue, May 06, 2014 at 11:53:36AM +0200, Daniel Mack wrote:
> On 05/06/2014 02:38 AM, Wang Nan wrote:
> > This patch fixs a problem introduced by commit e5d6a55 which make ARM
> > kexec fails.
> > Due to that commit, kernel is loaded at a dynamically offset: it computes
> > extra_size using size of dtb, and load zImage at base + extra_size. When
> > dtb size small (for example, 0x3000 bytes), kernel will be loaded at
> > address like 0x60003000. For ARM zImage such address is incorrect.
> > In kernel code arch/arm/boot/compressed/head.S, zImage builds a
> > temporary page table at (pc & 0xf8000000) + TEXT_OFFSET - 0x4000. The
> > related instructions sequence is:
> > mov r4, pc
> > and r4, r4, #0xf8000000
> > add r4, r4, #TEXT_OFFSET @ (TEXT_OFFSET == 0x8000 on most platforms)
> > call cache_on
> > ...
> > call __armv7_mmu_cache_on
> > ...
> > call __setup_mmu
> > sub r3, r4, #16384 @ Page directory size
> > r3 becomes page table pointer.
> > When kernel is loaded at 0x60003000, page table is still built at
> > 0x60004000, which destroys kernel.
> > This patch make extra_size a fix value (0x8000) to avoid the failure.
> > For the problem commit e5d6a55 tries solve, this patch uses
> > locate_holes() to find a place can hold initrd and dtb.
> > Change from v1:
> > - Coding style enhancements.
> > Signed-off-by: Wang Nan <wangnan0 at huawei.com>
> > Cc: Daniel Mack <zonque at gmail.com>
> Tested-by: Daniel Mack <zonque at gmail.com>
> Many thanks again for the fix and the elaboration!
Thanks, and apologies for the delay.
I am currently returning from a weeks vacation.
I have applied this locally and will push it some
time after I get off the plane ride home.
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