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.
