Messages in this thread Patch in this message | | | Date | Thu, 12 Mar 2009 13:11:50 +0000 | From | "Jan Beulich" <> | Subject | [PATCH] x86: create a non-zero sized bm_pte only when needed |
| |
Impact: kernel image size reduction
Since in most configurations the pmd page needed maps the same range of virtual addresses which is also mapped by the earlier inserted one for covering FIX_DBGP_BASE, that page (and its insertion in the page tables) can be avoided altogether by detecting the condition at compile time.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
--- arch/x86/mm/ioremap.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-)
--- linux-2.6.29-rc7/arch/x86/mm/ioremap.c 2009-03-04 09:10:19.000000000 +0100 +++ 2.6.29-rc7-x86-avoid-bm_pte/arch/x86/mm/ioremap.c 2009-02-18 15:34:02.000000000 +0100 @@ -490,7 +490,12 @@ static int __init early_ioremap_debug_se early_param("early_ioremap_debug", early_ioremap_debug_setup); static __initdata int after_paging_init; -static pte_t bm_pte[PAGE_SIZE/sizeof(pte_t)] __page_aligned_bss; +#define __FIXADDR_TOP (-PAGE_SIZE) +static pte_t bm_pte[(__fix_to_virt(FIX_DBGP_BASE) + ^ __fix_to_virt(FIX_BTMAP_BEGIN)) >> PMD_SHIFT + ? PAGE_SIZE / sizeof(pte_t) : 0] __page_aligned_bss; +#undef __FIXADDR_TOP +static __initdata pte_t *bm_ptep; static inline pmd_t * __init early_ioremap_pmd(unsigned long addr) { @@ -505,6 +510,8 @@ static inline pmd_t * __init early_iorem static inline pte_t * __init early_ioremap_pte(unsigned long addr) { + if (!sizeof(bm_pte)) + return &bm_ptep[pte_index(addr)]; return &bm_pte[pte_index(addr)]; } @@ -516,8 +523,14 @@ void __init early_ioremap_init(void) printk(KERN_INFO "early_ioremap_init()\n"); pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN)); - memset(bm_pte, 0, sizeof(bm_pte)); - pmd_populate_kernel(&init_mm, pmd, bm_pte); + if (sizeof(bm_pte)) { + memset(bm_pte, 0, sizeof(bm_pte)); + pmd_populate_kernel(&init_mm, pmd, bm_pte); + } else { + bm_ptep = pte_offset_kernel(pmd, 0); + if (early_ioremap_debug) + printk(KERN_INFO "bm_ptep=%p\n", bm_ptep); + } /* * The boot-ioremap range spans multiple pmds, for which
| |