On Fri, 4 Jan 2013, Yinghai Lu wrote:
> We are not having max_pfn_mapped set correctly until init_memory_mapping.
>
> so don't print it initial value for 64bit
>
> Also need to use KERNEL_IMAGE_SIZE directly for highmap cleanup.
>
> Signed-off-by: Yinghai Lu <[email protected]>
> ---
> arch/x86/kernel/head64.c | 3 ---
> arch/x86/kernel/setup.c | 2 ++
> arch/x86/mm/init_64.c | 6 +++++-
> 3 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index a3fc233..7061d8b 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -146,9 +146,6 @@ void __init x86_64_start_kernel(char * real_mode_data)
> /* clear bss before set_intr_gate with early_idt_handler */
> clear_bss();
>
> - /* XXX - this is wrong... we need to build page tables from scratch */
> - max_pfn_mapped = KERNEL_IMAGE_SIZE >> PAGE_SHIFT;
> -
> for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) {
> #ifdef CONFIG_EARLY_PRINTK
> set_intr_gate(i, &early_idt_handlers[i]);
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 63160c6..04797e78 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -910,8 +910,10 @@ void __init setup_arch(char **cmdline_p)
> setup_bios_corruption_check();
> #endif
>
> +#ifdef CONFIG_X86_32
> printk(KERN_DEBUG "initial memory mapped: [mem 0x00000000-%#010lx]\n",
> (max_pfn_mapped<<PAGE_SHIFT) - 1);
> +#endif
>
> reserve_real_mode();
>
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 9c5f2b1..98385a2 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -394,10 +394,14 @@ 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;
> 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 */
> + if (max_pfn_mapped)
> + vaddr_end = __START_KERNEL_map + (max_pfn_mapped << PAGE_SHIFT);
If you are going to put a comment like that in the code, could you
please at least add some useful details, rather than a generic
"somehow"? It doesn't seem very helpful to me or to any other hackers
looking at the code.
The issue is even described as a comment in the code at the beginning of
arch/x86/xen/mmu.c:xen_setup_kernel_pagetable:
/* max_pfn_mapped is the last pfn mapped in the initial memory
* mappings. Considering that on Xen after the kernel mappings we
* have the mappings of some pages that don't exist in pfn space, we
* set max_pfn_mapped to the last real pfn mapped. */
Now if max_pfn_mapped is supposed to represent the last pfn mapped in
the initial memory mapping, then I think that the way Xen uses
max_pfn_mapped is actually correct.
The question is: has max_pfn_mapped actually changed meaning?
Because if it hasn't I don't see why you need this change.
> for (; vaddr + PMD_SIZE - 1 < vaddr_end; pmd++, vaddr += PMD_SIZE) {
> if (pmd_none(*pmd))
> continue;
> --
> 1.7.10.4
>
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