Messages in this thread | | | Date | Fri, 21 Dec 2012 14:44:39 -0800 | Subject | Re: [PATCH v5 12/13] x86, 64bit: Print init kernel lowmap correctly | From | Yinghai Lu <> |
| |
On Fri, Dec 21, 2012 at 2:26 PM, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote: >> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c >> index 4178530..30f6190 100644 >> --- a/arch/x86/mm/init_64.c >> +++ b/arch/x86/mm/init_64.c >> @@ -304,10 +304,14 @@ void __init init_extra_mapping_uc(unsigned long phys, unsigned long size) >> void __init cleanup_highmap(void) >> { >> unsigned long vaddr = __START_KERNEL_map; >> - unsigned long vaddr_end = __START_KERNEL_map + (max_pfn_mapped << PAGE_SHIFT); >> + unsigned long vaddr_end = __START_KERNEL_map + KERNEL_IMAGE_SIZE; > > Should you remove the line in head64.c that sets the > max_pfn_mapped to KERNEL_IMAGE_SIZE >> PAGE_SHIFT? > >> unsigned long end = roundup((unsigned long)_brk_end, PMD_SIZE) - 1; >> pmd_t *pmd = level2_kernel_pgt; >> >> + /* Xen has its own end somehow with abused max_pfn_mapped */ > > Could you clarify please? > > My recollection is that the max_pfn_mapped would point to the end of the > RAMdisk. And yes (from mmu.c): > > 1862 /* max_pfn_mapped is the last pfn mapped in the initial memory > 1863 * mappings. Considering that on Xen after the kernel mappings we > 1864 * have the mappings of some pages that don't exist in pfn space, we > 1865 * set max_pfn_mapped to the last real pfn mapped. */ > 1866 max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->mfn_list)); > 1867 > > And if you follow xen_start_info, you get to include/xen/interface/xen.h which has: > > 406 * 4. This the order of bootstrap elements in the initial virtual region: > 407 * a. relocated kernel image > 408 * b. initial ram disk [mod_start, mod_len] > 409 * c. list of allocated page frames [mfn_list, nr_pages] > > so per that code I believe max_pfn_mapped covers the kernel and the ramdisk - no more. >
for native path, in x86_64_start_kernel, we set max_pfn_mapped wrongly (my fault , I messed up low mapping and high mapping). before this patchset, low_mapping end before end of x86_64_start_kernel is 1G, and high mapping end is 512M.
max_pfn_mapped is for low mapping.
in this patch, for native patch, we keep max_pfn_mapped untouched, so before clean_highmap, it will be 0.
so we check !max_pfn_mapped to make xen still work.
> >> + if (max_pfn_mapped) >> + vaddr_end = __START_KERNEL_map + (max_pfn_mapped << PAGE_SHIFT); >> + >> for (; vaddr + PMD_SIZE - 1 < vaddr_end; pmd++, vaddr += PMD_SIZE) { >> if (pmd_none(*pmd)) >> continue; >> -- > > This part of the patch does not seem to have much to do with the printk? > Should it be seperate patch?
maybe we can change the subject of this patch to:
Subject: [PATCH] x86, 64bit: Don't set max_pfn_mapped wrong on native boot path
?
| |