Messages in this thread Patch in this message | | | Date | Sun, 16 Sep 2018 23:06:41 +0800 | From | Feng Tang <> | Subject | Re: [PATCH] x86, mm: Reserver some memory for bootmem allocator for NO_BOOTMEM |
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Hi Thomas,
On Sun, Sep 16, 2018 at 04:43:55PM +0200, Thomas Gleixner wrote: > On Sun, 16 Sep 2018, Feng Tang wrote: > > diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c > > index e848a4811785..a927f5f39bee 100644 > > --- a/arch/x86/mm/pgtable.c > > +++ b/arch/x86/mm/pgtable.c > > @@ -637,6 +637,16 @@ void __native_set_fixmap(enum fixed_addresses idx, pte_t pte) > > { > > unsigned long address = __fix_to_virt(idx); > > > > +#ifdef CONFIG_X86_64 > > + /* > > + * In arch/x86/kernel/head_64.S, the static page table has > > + * been setup for fixmap. Add a sanity compiling check > > + * whether fixmap space has exceeded the capacity. > > + */ > > + BUILD_BUG_ON((__end_of_permanent_fixed_addresses + 511)/512 > > + > FIXMAP_PMD_NUM); > > There exist macros for rounding up and doing this in the header file is > perfectly fine.
I'll find the sample for the round up.
And for the header file check, I initially put this check directly in the fixmap.h like:
#if ((__end_of_permanent_fixed_addresses + 511)/512 > FIXMAP_PMD_NUM) #erro "some warning...." #endif
But failed to compile, I got the warning warning: "__end_of_permanent_fixed_addresses" is not defined
I guess the header file preprocessing can't handle it.
> > > +#endif > > + > > if (idx >= __end_of_fixed_addresses) { > > BUG(); > > return; > > diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c > > index 45b700ac5fe7..b0aa2364a3c6 100644 > > --- a/arch/x86/xen/mmu_pv.c > > +++ b/arch/x86/xen/mmu_pv.c > > @@ -1953,7 +1953,10 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn) > > set_page_prot(level2_ident_pgt, PAGE_KERNEL_RO); > > set_page_prot(level2_kernel_pgt, PAGE_KERNEL_RO); > > set_page_prot(level2_fixmap_pgt, PAGE_KERNEL_RO); > > - set_page_prot(level1_fixmap_pgt, PAGE_KERNEL_RO); > > + > > + for (i = 0; i < FIXMAP_PMD_NUM; i++) > > + set_page_prot(level1_fixmap_pgt + i * 512, > > + PAGE_KERNEL_RO); > > The line break is there because? Will fix it. I used a MACRO before changing to 512 and forgot to remove the line break :)
Thanks, Feng
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