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| author | Ingo Molnar <mingo@elte.hu> | 2008-02-21 11:04:11 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-02-26 12:55:56 +0100 |
| commit | 88f3aec7afd9ae3e6f6d221801996b69aad1e3a4 (patch) | |
| tree | 676a32c7bd248a15f2926bc6dcd03ace4971d442 /arch/x86 | |
| parent | 3b57bc461fd5019aef4cfc77d4faf56ebe95449c (diff) | |
| download | op-kernel-dev-88f3aec7afd9ae3e6f6d221801996b69aad1e3a4.zip op-kernel-dev-88f3aec7afd9ae3e6f6d221801996b69aad1e3a4.tar.gz | |
x86: fix spontaneous reboot with allyesconfig bzImage
recently the 64-bit allyesconfig bzImage kernel started spontaneously
rebooting during early bootup.
after a few fun hours spent with early init debugging, it turns out
that we've got this rather annoying limit on the size of the kernel
image:
#define KERNEL_TEXT_SIZE (40*1024*1024)
which limit my vmlinux just happened to pass:
text data bss dec hex filename
29703744 4222751 8646224 42572719 2899baf vmlinux
40 MB is 42572719 bytes, so my vmlinux was just 1.5% above this limit :-/
So it happily crashed right in head_64.S, which - as we all know - is
the most debuggable code in the whole architecture ;-)
So increase the limit to allow an up to 128MB kernel image to be mapped.
(should anyone be that crazy or lazy)
We have a full 4K of pagetable (level2_kernel_pgt) allocated for these
mappings already, so there's no RAM overhead and the limit was rather
pointless and arbitrary.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/head_64.S | 22 | ||||
| -rw-r--r-- | arch/x86/mm/init_64.c | 5 |
2 files changed, 17 insertions, 10 deletions
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index eb41504..b037b15 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -379,18 +379,24 @@ NEXT_PAGE(level2_ident_pgt) /* Since I easily can, map the first 1G. * Don't set NX because code runs from these pages. */ - PMDS(0x0000000000000000, __PAGE_KERNEL_LARGE_EXEC, PTRS_PER_PMD) + PMDS(0, __PAGE_KERNEL_LARGE_EXEC, PTRS_PER_PMD) NEXT_PAGE(level2_kernel_pgt) - /* 40MB kernel mapping. The kernel code cannot be bigger than that. - When you change this change KERNEL_TEXT_SIZE in page.h too. */ - /* (2^48-(2*1024*1024*1024)-((2^39)*511)-((2^30)*510)) = 0 */ - PMDS(0x0000000000000000, __PAGE_KERNEL_LARGE_EXEC|_PAGE_GLOBAL, KERNEL_TEXT_SIZE/PMD_SIZE) - /* Module mapping starts here */ - .fill (PTRS_PER_PMD - (KERNEL_TEXT_SIZE/PMD_SIZE)),8,0 + /* + * 128 MB kernel mapping. We spend a full page on this pagetable + * anyway. + * + * The kernel code+data+bss must not be bigger than that. + * + * (NOTE: at +128MB starts the module area, see MODULES_VADDR. + * If you want to increase this then increase MODULES_VADDR + * too.) + */ + PMDS(0, __PAGE_KERNEL_LARGE_EXEC|_PAGE_GLOBAL, + KERNEL_TEXT_SIZE/PMD_SIZE) NEXT_PAGE(level2_spare_pgt) - .fill 512,8,0 + .fill 512, 8, 0 #undef PMDS #undef NEXT_PAGE diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 6dbb003..a02a14f 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -172,8 +172,9 @@ set_pte_phys(unsigned long vaddr, unsigned long phys, pgprot_t prot) } /* - * The head.S code sets up the kernel high mapping from: - * __START_KERNEL_map to __START_KERNEL_map + KERNEL_TEXT_SIZE + * The head.S code sets up the kernel high mapping: + * + * from __START_KERNEL_map to __START_KERNEL_map + size (== _end-_text) * * phys_addr holds the negative offset to the kernel, which is added * to the compile time generated pmds. This results in invalid pmds up |
