Messages in this thread Patch in this message | | | Date | Wed, 2 Aug 2006 00:01:47 -0700 | From | Chris Wright <> | Subject | Re: [PATCH 7 of 13] Make __FIXADDR_TOP variable to allow it to make space for a hypervisor |
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* Rusty Russell (rusty@rustcorp.com.au) wrote: > On Tue, 2006-08-01 at 14:37 -0700, Chris Wright wrote: > > * Andrew Morton (akpm@osdl.org) wrote: > > > On Tue, 1 Aug 2006 02:03:30 -0700 > > > Chris Wright <chrisw@sous-sol.org> wrote: > > > > > > > * Jeremy Fitzhardinge (jeremy@xensource.com) wrote: > > > > > -#define MAXMEM (-__PAGE_OFFSET-__VMALLOC_RESERVE) > > > > > +#define MAXMEM (__FIXADDR_TOP-__PAGE_OFFSET-__VMALLOC_RESERVE) > > > > > > > > In the native case we lose one page of lowmem now. > > > > > > erm, isn't this the hunk which gave one of my machines a 4kb highmem zone? > > > I have memories of reverting it. > > > > Yes, that does sound quite familiar. I couldn't find the thread, do you > > recall any of the details? I expect it's the same issue as the off by one > > page I mentioned above. > > Good catch Andrew. I did say we'd fix this. Will frob this patch > further...
Here's an updated patch. Rather than use __FIXADDR_TOP to adjust for MAXMEM, directly update __VMALLOC_RESERVE which is used to reserve the space for vmalloc, iomap, and fixmap (as comments aptly point out). I tested this with a bunch of configurations, and booted a XenoLinux kernel with this patch as well.
thanks, -chris --
Make __FIXADDR_TOP variable to allow it to make space for a hypervisor.
Make __FIXADDR_TOP a variable, so that it can be set to not get in the way of address space a hypervisor may want to reserve.
Original patch by Gerd Hoffmann <kraxel@suse.de>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Cc: Gerd Hoffmann <kraxel@suse.de>
--- arch/i386/Kconfig | 1 + arch/i386/mm/init.c | 42 ++++++++++++++++++++++++++++++++++++++++++ arch/i386/mm/pgtable.c | 19 +++++++++++++++++++ include/asm-i386/fixmap.h | 7 ++++++- 4 files changed, 68 insertions(+), 1 deletion(-)
diff -r 5183f1f33cf4 arch/i386/Kconfig --- a/arch/i386/Kconfig Tue Aug 01 01:06:48 2006 -0400 +++ b/arch/i386/Kconfig Wed Aug 02 02:34:44 2006 -0400 @@ -792,6 +792,7 @@ config COMPAT_VDSO config COMPAT_VDSO bool "Compat VDSO support" default y + depends on !PARAVIRT help Map the VDSO to the predictable old-style address too. ---help--- diff -r 5183f1f33cf4 arch/i386/mm/init.c --- a/arch/i386/mm/init.c Tue Aug 01 01:06:48 2006 -0400 +++ b/arch/i386/mm/init.c Wed Aug 02 02:34:44 2006 -0400 @@ -629,6 +629,48 @@ void __init mem_init(void) (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10)) ); +#if 1 /* double-sanity-check paranoia */ + printk("virtual kernel memory layout:\n" + " fixmap : 0x%08lx - 0x%08lx (%4ld kB)\n" +#ifdef CONFIG_HIGHMEM + " pkmap : 0x%08lx - 0x%08lx (%4ld kB)\n" +#endif + " vmalloc : 0x%08lx - 0x%08lx (%4ld MB)\n" + " lowmem : 0x%08lx - 0x%08lx (%4ld MB)\n" + " .init : 0x%08lx - 0x%08lx (%4ld kB)\n" + " .data : 0x%08lx - 0x%08lx (%4ld kB)\n" + " .text : 0x%08lx - 0x%08lx (%4ld kB)\n", + FIXADDR_START, FIXADDR_TOP, + (FIXADDR_TOP - FIXADDR_START) >> 10, + +#ifdef CONFIG_HIGHMEM + PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE, + (LAST_PKMAP*PAGE_SIZE) >> 10, +#endif + + VMALLOC_START, VMALLOC_END, + (VMALLOC_END - VMALLOC_START) >> 20, + + (unsigned long)__va(0), (unsigned long)high_memory, + ((unsigned long)high_memory - (unsigned long)__va(0)) >> 20, + + (unsigned long)&__init_begin, (unsigned long)&__init_end, + ((unsigned long)&__init_end - (unsigned long)&__init_begin) >> 10, + + (unsigned long)&_etext, (unsigned long)&_edata, + ((unsigned long)&_edata - (unsigned long)&_etext) >> 10, + + (unsigned long)&_text, (unsigned long)&_etext, + ((unsigned long)&_etext - (unsigned long)&_text) >> 10); + +#ifdef CONFIG_HIGHMEM + BUG_ON(PKMAP_BASE+LAST_PKMAP*PAGE_SIZE > FIXADDR_START); + BUG_ON(VMALLOC_END > PKMAP_BASE); +#endif + BUG_ON(VMALLOC_START > VMALLOC_END); + BUG_ON((unsigned long)high_memory > VMALLOC_START); +#endif /* double-sanity-check paranoia */ + #ifdef CONFIG_X86_PAE if (!cpu_has_pae) panic("cannot execute a PAE-enabled kernel on a PAE-less CPU!"); diff -r 5183f1f33cf4 arch/i386/mm/pgtable.c --- a/arch/i386/mm/pgtable.c Tue Aug 01 01:06:48 2006 -0400 +++ b/arch/i386/mm/pgtable.c Wed Aug 02 02:34:44 2006 -0400 @@ -12,6 +12,7 @@ #include <linux/slab.h> #include <linux/pagemap.h> #include <linux/spinlock.h> +#include <linux/module.h> #include <asm/system.h> #include <asm/pgtable.h> @@ -137,6 +138,12 @@ void set_pmd_pfn(unsigned long vaddr, un __flush_tlb_one(vaddr); } +static int fixmaps; +#ifndef CONFIG_COMPAT_VDSO +unsigned long __FIXADDR_TOP = 0xfffff000; +EXPORT_SYMBOL(__FIXADDR_TOP); +#endif + void __set_fixmap (enum fixed_addresses idx, unsigned long phys, pgprot_t flags) { unsigned long address = __fix_to_virt(idx); @@ -146,6 +153,18 @@ void __set_fixmap (enum fixed_addresses return; } set_pte_pfn(address, phys >> PAGE_SHIFT, flags); + fixmaps++; +} + +void set_fixaddr_top(unsigned long top) +{ + BUG_ON(fixmaps > 0); +#ifdef CONFIG_COMPAT_VDSO + BUG_ON(top - PAGE_SIZE != __FIXADDR_TOP); +#else + __FIXADDR_TOP = top - PAGE_SIZE; + __VMALLOC_RESERVE -= top; +#endif } pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address) diff -r 5183f1f33cf4 include/asm-i386/fixmap.h --- a/include/asm-i386/fixmap.h Tue Aug 01 01:06:48 2006 -0400 +++ b/include/asm-i386/fixmap.h Wed Aug 02 02:34:44 2006 -0400 @@ -19,7 +19,11 @@ * Leave one empty page between vmalloc'ed areas and * the start of the fixmap. */ -#define __FIXADDR_TOP 0xfffff000 +#ifndef CONFIG_COMPAT_VDSO +extern unsigned long __FIXADDR_TOP; +#else +#define __FIXADDR_TOP 0xfffff000 +#endif #ifndef __ASSEMBLY__ #include <linux/kernel.h> @@ -93,6 +97,7 @@ enum fixed_addresses { extern void __set_fixmap (enum fixed_addresses idx, unsigned long phys, pgprot_t flags); +extern void set_fixaddr_top(unsigned long top); #define set_fixmap(idx, phys) \ __set_fixmap(idx, phys, PAGE_KERNEL) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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