[PATCH] ppc64 need HPAGE_SHIFT when huge pages disabled
Andrew Morton
akpm at osdl.org
Fri Nov 18 08:11:20 EST 2005
Andy Whitcroft <apw at shadowen.org> wrote:
>
> With the new powerpc architecture we don't seem to be able to disable
> huge pages anymore.
>
> mm/built-in.o(.toc1+0xae0): undefined reference to `HPAGE_SHIFT'
> make: *** [.tmp_vmlinux1] Error 1
>
> We seem to need to define HPAGE_SHIFT to something when HUGETLB_PAGE isn't
> defined. This patch defines it to 0 when we have no support.
>
Yes, i386 defines HPAGE_SHIFT always.
>
> Signed-off-by: Andy Whitcroft <apw at shadowen.org>
> ---
> diff -upN reference/include/asm-powerpc/page_64.h current/include/asm-powerpc/page_64.h
> --- reference/include/asm-powerpc/page_64.h
> +++ current/include/asm-powerpc/page_64.h
> @@ -86,7 +86,11 @@ static inline void copy_page(void *to, v
> extern u64 ppc64_pft_size;
>
> /* Large pages size */
> +#ifdef CONFIG_HUGETLB_PAGE
> extern unsigned int HPAGE_SHIFT;
> +#else
> +#define HPAGE_SHIFT 0
> +#endif
> #define HPAGE_SIZE ((1UL) << HPAGE_SHIFT)
> #define HPAGE_MASK (~(HPAGE_SIZE - 1))
> #define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT)
I think this change will cause a compile warning in mm/memory.c:
if (unlikely(is_vm_hugetlb_page(vma))) {
unmap_hugepage_range(vma, start, end);
zap_work -= (end - start) /
(HPAGE_SIZE / PAGE_SIZE);
This code will be removed by the compiler. But before that happens, we're
doing a divide by zero and the compiler will whine.
So I'd suggest that you set the !CONFIG_HUGETLB_PAGE value of HPAGE_SHIFT
to PAGE_SHIFT, not to zero. I'll make that change locally..
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