On Fri, Dec 21, 2012 at 2:26 PM, Konrad Rzeszutek Wilk
<[email protected]> 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
?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
