Messages in this thread Patch in this message | | | Date | Fri, 8 Aug 2008 15:04:33 +1000 | From | Simon Horman <> | Subject | Allow compile with CONFIG_DEBUG_INFO=y, X86_PAE not set on gcc 3.4.5 |
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Hi,
It appears that "x86: preallocate and prepopulate separately" (d8d5900ef8afc562088f8470feeaf17c4747790f) introduced a minor regression. The build fails on gcc 3.4.5 if CONFIG_DEBUG_INFO=y (that is gcc is called with -g) and X86_PAE not set.
There was previously some discussion of this without resolution. http://lkml.org/lkml/2008/7/18/250
arch/x86/mm/pgtable.c: In function `pgd_prepopulate_pmd': arch/x86/mm/pgtable.c:222: internal compiler error: in remove_insn, at emit-rtl.c:3746 Please submit a full bug report, with preprocessed source if appropriate. See <URL:http://gcc.gnu.org/bugs.html> for instructions.
# i686-unknown-linux-gnu-gcc --version i686-unknown-linux-gnu-gcc (GCC) 3.4.5
My investigations seem to show that gcc 3.4.5 can't cope with the following construct:
for (i = 0; i < 0; i++) ...
or more specifically:
for (i = 0; i < PREALLOCTED_PMDS; i++) ...
when PREALLOCTED_PMDS is 0. That is, when X86_PAE is not set.
This patch resolves this problem by moving the relevant code inside #define X86_PAE and providing dummy functions outside !X86_PAE.
Signed-off-by: Simon Horman <horms@verge.net.au>
Index: linux-2.6/arch/x86/mm/pgtable.c =================================================================== --- linux-2.6.orig/arch/x86/mm/pgtable.c 2008-08-08 14:35:29.000000000 +1000 +++ linux-2.6/arch/x86/mm/pgtable.c 2008-08-08 15:00:07.000000000 +1000 @@ -141,12 +141,6 @@ void pud_populate(struct mm_struct *mm, if (mm == current->active_mm) write_cr3(read_cr3()); } -#else /* !CONFIG_X86_PAE */ - -/* No need to prepopulate any pagetable entries in non-PAE modes. */ -#define PREALLOCATED_PMDS 0 - -#endif /* CONFIG_X86_PAE */ static void free_pmds(pmd_t *pmds[]) { @@ -221,6 +215,19 @@ static void pgd_prepopulate_pmd(struct m } } +#else /* !CONFIG_X86_PAE */ + +/* No need to prepopulate any pagetable entries in non-PAE modes. */ +#define PREALLOCATED_PMDS 0 + +static int preallocate_pmds(pmd_t *pmds[]) { return 0; } +static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[]) +{ } +static void free_pmds(pmd_t *pmds[]) { } +static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgdp) { } + +#endif /* CONFIG_X86_PAE */ + pgd_t *pgd_alloc(struct mm_struct *mm) { pgd_t *pgd;
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