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We need to map in some memory areas >8MB just to find out how much
memory we have, and where it is. (the e820 table doesn't cut it on this
hardware)
This is only intended for remapping while the boot-time pagetables are
still in use. It was a pain to get the 2-level pgtable.h functions, so
I just undef'd CONFIG_X86_PAE for my file. It looks awfully hackish,
but it works well.
Some of my colleagues (Martin) would prefer to steal ptes from some
other source (just pick the last N from pg1), then replace them when the
remapping is done. I don't really like this approach. I prefer to know
exactly where I'm stealing them from, which is where boot_ioremap_area[]
comes in.
I would be amenable to making this dependent on some config option set
via CONFIG_X86_SUMMIT, to keep from bloating the normal kernel case
which doesn't use this code.
-- Dave Hansen haveblue@us.ibm.com--=_courier-24000-1045155142-0001-2 Content-Type: text/plain; name="early_ioremap-2.5.59-mjb5-1.patch"; charset=iso-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="early_ioremap-2.5.59-mjb5-1.patch"
diff -urN --exclude-from=/work/dave/linux/exclude linux-2.5.59-mjb5-clean/arch/i386/mm/Makefile linux-2.5.59-mjb5-pgtablefun/arch/i386/mm/Makefile --- linux-2.5.59-mjb5-clean/arch/i386/mm/Makefile Tue Feb 11 11:51:57 2003 +++ linux-2.5.59-mjb5-pgtablefun/arch/i386/mm/Makefile Wed Feb 12 23:13:08 2003 @@ -4,7 +4,7 @@ export-objs := pageattr.o -obj-y := init.o pgtable.o fault.o ioremap.o extable.o pageattr.o +obj-y := init.o pgtable.o fault.o ioremap.o extable.o pageattr.o boot_ioremap.o obj-$(CONFIG_DISCONTIGMEM) += discontig.o obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o diff -urN --exclude-from=/work/dave/linux/exclude linux-2.5.59-mjb5-clean/arch/i386/mm/boot_ioremap.c linux-2.5.59-mjb5-pgtablefun/arch/i386/mm/boot_ioremap.c --- linux-2.5.59-mjb5-clean/arch/i386/mm/boot_ioremap.c Wed Dec 31 16:00:00 1969 +++ linux-2.5.59-mjb5-pgtablefun/arch/i386/mm/boot_ioremap.c Wed Feb 12 23:16:32 2003 @@ -0,0 +1,94 @@ +/* + * arch/i386/mm/boot_ioremap.c + * + * Re-map functions for early boot-time before paging_init() when the + * boot-time pagetables are still in use + * + * Written by Dave Hansen <haveblue@us.ibm.com> + */ + + +/* + * We need to use the 2-level pagetable functions, but CONFIG_X86_PAE + * keeps that from happenning. If anyone has a better way, I'm listening. + * + * boot_pte_t is defined only if this all works correctly + */ + +#include <linux/config.h> +#undef CONFIG_X86_PAE +#include <asm/page.h> +#include <asm/pgtable.h> +#include <linux/init.h> +#include <linux/stddef.h> + +/* + * I'm cheating here. It is known that the two boot PTE pages are + * allocated next to each other. I'm pretending that they're just + * one big array. + */ + +#define BOOT_PTE_PTRS (PTRS_PER_PTE*2) +#define boot_pte_index(address) \ + (((address) >> PAGE_SHIFT) & (BOOT_PTE_PTRS - 1)) + +static inline boot_pte_t* boot_vaddr_to_pte(void *address) +{ + boot_pte_t* boot_pg = (boot_pte_t*)pg0; + return &boot_pg[boot_pte_index((unsigned long)address)]; +} + +/* + * This is only for a caller who is clever enough to page-align + * phys_addr and virtual_source, and who also has a preference + * about which virtual address from which to steal ptes + */ +static void __boot_ioremap(unsigned long phys_addr, unsigned long nrpages, + void* virtual_source) +{ + boot_pte_t* pte; + int i; + + pte = boot_vaddr_to_pte(virtual_source); + for (i=0; i < nrpages; i++, phys_addr += PAGE_SIZE, pte++) { + set_pte(pte, pfn_pte(phys_addr>>PAGE_OFFSET, PAGE_KERNEL)); + } +} + +/* the virtual space we're going to remap comes from this array */ +#define BOOT_IOREMAP_PAGES 4 +#define BOOT_IOREMAP_SIZE (BOOT_IOREMAP_PAGES*PAGE_SIZE) +__init char boot_ioremap_space[BOOT_IOREMAP_SIZE] + __attribute__ ((aligned (PAGE_SIZE))); + +/* + * This only applies to things which need to ioremap before paging_init() + * bt_ioremap() and plain ioremap() are both useless at this point. + * + * When used, we're still using the boot-time pagetables, which only + * have 2 PTE pages mapping the first 8MB + * + * There is no unmap. The boot-time PTE pages aren't used after boot. + * If you really want the space back, just remap it yourself. + * boot_ioremap(&ioremap_space-PAGE_OFFSET, BOOT_IOREMAP_SIZE) + */ +__init void* boot_ioremap(unsigned long phys_addr, unsigned long size) +{ + unsigned long last_addr, offset; + unsigned int nrpages; + + last_addr = phys_addr + size - 1; + + /* page align the requested address */ + offset = phys_addr & ~PAGE_MASK; + phys_addr &= PAGE_MASK; + size = PAGE_ALIGN(last_addr) - phys_addr; + + nrpages = size >> PAGE_SHIFT; + if (nrpages > BOOT_IOREMAP_PAGES) + return NULL; + + __boot_ioremap(phys_addr, nrpages, boot_ioremap_space); + + return &boot_ioremap_space[offset]; +} diff -urN --exclude-from=/work/dave/linux/exclude linux-2.5.59-mjb5-clean/include/asm-i386/page.h linux-2.5.59-mjb5-pgtablefun/include/asm-i386/page.h --- linux-2.5.59-mjb5-clean/include/asm-i386/page.h Tue Feb 11 12:39:46 2003 +++ linux-2.5.59-mjb5-pgtablefun/include/asm-i386/page.h Wed Feb 12 22:28:48 2003 @@ -49,6 +49,7 @@ typedef struct { unsigned long pte_low; } pte_t; typedef struct { unsigned long pmd; } pmd_t; typedef struct { unsigned long pgd; } pgd_t; +#define boot_pte_t pte_t /* or would you rather have a typedef */ #define pte_val(x) ((x).pte_low) #define HPAGE_SHIFT 22 #endif
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