On Thu, Mar 06, 2025 at 11:00:16PM +0100, Ingo Molnar wrote: > * Ingo Molnar <mingo@xxxxxxxxxx> wrote: > > > Separating out the assembler-compatible defines from the types > > headers appears to be a bigger patch, since it's all mixed in with C > > syntax: > > > > <=-----------------------------------=============================== > > typedef struct { pud_t pud; } pmd_t; > > > > #define PMD_SHIFT PUD_SHIFT > > #define PTRS_PER_PMD 1 > > #define PMD_SIZE (1UL << PMD_SHIFT) > > #define PMD_MASK (~(PMD_SIZE-1)) > > > > /* > > * The "pud_xxx()" functions here are trivial for a folded two-level > > * setup: the pmd is never bad, and a pmd always exists (as it's folded > > * into the pud entry) > > */ > > static inline int pud_none(pud_t pud) { return 0; } > > static inline int pud_bad(pud_t pud) { return 0; } > > static inline int pud_present(pud_t pud) { return 1; } > > ================================================================> > > > > In any case I've removed the commit for the time being until this all > > is cleared up. > > So there's a simple solution: define it on i386 too, via the patch > below. It appears the double-definition doesn't create any warnings, on > GCC at least. Fine by me as long as it gets fixed. Currently it prevents the WERROR=y to be used along with `make W=1` for x86_32 by both compilers. > But if it's an issue, we could do something like this in > <asm-generic/pgtable-nopmd.h>: > > #if defined(PTRS_PER_PMD) && (PTRS_PER_PMD != 1) > # error "mm: Wait a minute, that's a super confusing pagetable setup ..." > #endif > > ? > > Thanks, > > Ingo > > =========================> > From: Ingo Molnar <mingo@xxxxxxxxxx> > Date: Thu, 6 Mar 2025 22:53:49 +0100 > Subject: [PATCH] x86/mm: Define PTRS_PER_PMD for assembly code too > > Andy reported the following build warning from head_32.S: > > In file included from arch/x86/kernel/head_32.S:29: > arch/x86/include/asm/pgtable_32.h:59:5: error: "PTRS_PER_PMD" is not defined, evaluates to 0 [-Werror=undef] > 59 | #if PTRS_PER_PMD > 1 > > The reason is that on 2-level i386 paging the folded in PMD's > PTRS_PER_PMD constant is not defined in assembly headers, > only in generic MM C headers. > > Instead of trying to fish out the definition from the generic > headers, just define it - it even has a comment for it already... > > Reported-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> > --- > arch/x86/include/asm/pgtable-2level_types.h | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/pgtable-2level_types.h b/arch/x86/include/asm/pgtable-2level_types.h > index 7f6ccff0ba72..4a12c276b181 100644 > --- a/arch/x86/include/asm/pgtable-2level_types.h > +++ b/arch/x86/include/asm/pgtable-2level_types.h > @@ -23,17 +23,17 @@ typedef union { > #define ARCH_PAGE_TABLE_SYNC_MASK PGTBL_PMD_MODIFIED > > /* > - * traditional i386 two-level paging structure: > + * Traditional i386 two-level paging structure: > */ > > #define PGDIR_SHIFT 22 > #define PTRS_PER_PGD 1024 > > - > /* > - * the i386 is two-level, so we don't really have any > - * PMD directory physically. > + * The i386 is two-level, so we don't really have any > + * PMD directory physically: > */ > +#define PTRS_PER_PMD 1 Should I give a try? Okay, just Tested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> for x86_32 with Clang 19.1.7 and GCC 14.2.0. -- With Best Regards, Andy Shevchenko
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