On Sat, Jan 27, 2018 at 11:22:15AM +0800, Huacai Chen wrote: > KEXEC assume kernel align to PAGE_SIZE, and 64KB is the largest > PAGE_SIZE. Please expand, maybe referring to sanity_check_segment_list() which does the actual check. Maybe something like this: Kexec needs the new kernel's load address to be aligned on a page boundary (see sanity_check_segment_list()), but on MIPS the default vmlinuz load address is only explicitly aligned to 16 bytes. Since the largest PAGE_SIZE supported by MIPS kernels is 64KB, increase the alignment calculated by calc_vmlinuz_load_addr to 64KB. I suppose it'd be a bit ugly for the kexec userland code to increase the size of the load segment downwards to make it page aligned... > > Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx> > --- > arch/mips/boot/compressed/calc_vmlinuz_load_addr.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/arch/mips/boot/compressed/calc_vmlinuz_load_addr.c b/arch/mips/boot/compressed/calc_vmlinuz_load_addr.c > index 37fe58c..1dcaef4 100644 > --- a/arch/mips/boot/compressed/calc_vmlinuz_load_addr.c > +++ b/arch/mips/boot/compressed/calc_vmlinuz_load_addr.c > @@ -45,11 +45,10 @@ int main(int argc, char *argv[]) > vmlinuz_load_addr = vmlinux_load_addr + vmlinux_size; > > /* > - * Align with 16 bytes: "greater than that used for any standard data > - * types by a MIPS compiler." -- See MIPS Run Linux (Second Edition). > + * Align with 64KB: KEXEC assume kernel align to PAGE_SIZE "Align to 64KB: kexec needs load sections to be aligned to PAGE_SIZE, which may be as large as 64KB depending on the kernel configuration". > */ > > - vmlinuz_load_addr += (16 - vmlinux_size % 16); > + vmlinuz_load_addr += (65536 - vmlinux_size % 65536); Personally I find (64 * 1024) (or even SZ_64K) easier to read, but no big deal. Thanks James
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