From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762982AbZCNAx1 (ORCPT ); Fri, 13 Mar 2009 20:53:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756565AbZCNAXJ (ORCPT ); Fri, 13 Mar 2009 20:23:09 -0400 Received: from gw.goop.org ([64.81.55.164]:55611 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756633AbZCNAXI (ORCPT ); Fri, 13 Mar 2009 20:23:08 -0400 Message-ID: <49BAF8E8.5000602@goop.org> Date: Fri, 13 Mar 2009 17:23:04 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: Yinghai Lu CC: "H. Peter Anvin" , Ingo Molnar , the arch/x86 maintainers , "Eric W. Biederman" , Linux Kernel Mailing List Subject: Re: [GIT PULL] x86: add brk allocator for very early allocations References: <49B7EDF4.7060904@goop.org> <49B800B8.2040009@kernel.org> <49B9A1CD.5040704@goop.org> <49B9AC7F.9030302@kernel.org> <49BAC1B0.6050107@goop.org> <49BAE210.7090300@zytor.com> <49BAE55F.40406@goop.org> <49BAEA3B.8030808@kernel.org> In-Reply-To: <49BAEA3B.8030808@kernel.org> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Yinghai Lu wrote: > Jeremy Fitzhardinge wrote: > >> H. Peter Anvin wrote: >> >>> Those references are just the actual reservation of memory. If all >>> the users of that memory are converted to either brk or bss, >>> INIT_MAP_BEYOND_END should be removed. If all the users of that >>> memory aren't converted to brk to bss, we should do so. >>> >> I just added an adapted Yinghai's patch and added it to push/x86/brk. >> >> J >> >> >> The following changes since commit >> 8131667360004a0b74e4dcadfee8a18d4e2b074f: >> Jeremy Fitzhardinge (1): >> x86: allow extend_brk users to reserve brk space >> >> are available in the git repository at: >> >> git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git push/x86/brk >> >> Yinghai Lu (1): >> x86: put initial_pg_tables into .bss -v4 >> >> arch/x86/kernel/head_32.S | 47 >> ++++++++++++++----------------------- >> arch/x86/kernel/vmlinux_32.lds.S | 6 +++++ >> 2 files changed, 24 insertions(+), 29 deletions(-) >> >> diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S >> index 80dc05e..ad7dbbb 100644 >> --- a/arch/x86/kernel/head_32.S >> +++ b/arch/x86/kernel/head_32.S >> @@ -38,42 +38,30 @@ >> #define X86_VENDOR_ID new_cpu_data+CPUINFO_x86_vendor_id >> >> /* >> - * This is how much memory *in addition to the memory covered up to >> - * and including _end* we need mapped initially. >> - * We need: >> - * - one bit for each possible page, but only in low memory, which means >> - * 2^32/4096/8 = 128K worst case (4G/4G split.) >> + * This is how much memory for page table to and including _end >> + * we need mapped initially. >> * - enough space to map all low memory, which means >> - * (2^32/4096) / 1024 pages (worst case, non PAE) >> - * (2^32/4096) / 512 + 4 pages (worst case for PAE) >> - * - a few pages for allocator use before the kernel pagetable has >> - * been set up >> + * (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE) >> + * (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE) >> * >> * Modulo rounding, each megabyte assigned here requires a kilobyte of >> * memory, which is currently unreclaimed. >> * >> * This should be a multiple of a page. >> + * >> + * KERNEL_IMAGE_SIZE should be greater than pa(_end) >> + * and small than max_low_pfn, otherwise will waste some page table >> entries >> */ >> LOW_PAGES = (KERNEL_IMAGE_SIZE + PAGE_SIZE_asm - 1)>>PAGE_SHIFT >> >> -/* >> - * To preserve the DMA pool in PAGEALLOC kernels, we'll allocate >> - * pagetables from above the 16MB DMA limit, so we'll have to set >> - * up pagetables 16MB more (worst-case): >> - */ >> -#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK) >> -LOW_PAGES = LOW_PAGES + 0x1000000 >> -#endif >> - >> #if PTRS_PER_PMD > 1 >> PAGE_TABLE_SIZE = (LOW_PAGES / PTRS_PER_PMD) + PTRS_PER_PGD >> #else >> PAGE_TABLE_SIZE = (LOW_PAGES / PTRS_PER_PGD) >> #endif >> -BOOTBITMAP_SIZE = LOW_PAGES / 8 >> ALLOCATOR_SLOP = 4 >> >> -INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + (PAGE_TABLE_SIZE + >> ALLOCATOR_SLOP)*PAGE_SIZE_asm >> +INIT_MAP_SIZE = (PAGE_TABLE_SIZE + ALLOCATOR_SLOP) * PAGE_SIZE_asm >> >> RESERVE_BRK(pagetables, PAGE_TABLE_SIZE * PAGE_SIZE) >> > > use INIT_MAP_SIZE in RESERVE_BRK directly? > OK. > >> @@ -168,10 +156,10 @@ num_subarch_entries = (. - subarch_entries) / 4 >> >> /* >> * Initialize page tables. This creates a PDE and a set of page >> - * tables, which are located immediately beyond _end. The variable >> + * tables, which are located immediately beyond __brk_base. The variable >> * _brk_end is set up to point to the first "safe" location. >> * Mappings are created both at virtual address 0 (identity mapping) >> - * and PAGE_OFFSET for up to _end+sizeof(page tables)+INIT_MAP_BEYOND_END. >> + * and PAGE_OFFSET for up to _end. >> * >> * Note that the stack is not yet set up! >> */ >> @@ -210,10 +198,9 @@ default_entry: >> loop 11b >> >> /* >> - * End condition: we must map up to and including INIT_MAP_BEYOND_END >> - * bytes beyond the end of our own page tables. >> + * End condition: we must map up to the end. >> */ >> - leal (INIT_MAP_BEYOND_END+PTE_IDENT_ATTR)(%edi),%ebp >> + movl $pa(_end) + PTE_IDENT_ATTR, %ebp >> cmpl %ebp,%eax >> jb 10b >> 1: >> @@ -243,11 +230,9 @@ page_pde_offset = (__PAGE_OFFSET >> 20); >> addl $0x1000,%eax >> loop 11b >> /* >> - * End condition: we must map up to and including INIT_MAP_BEYOND_END >> - * bytes beyond the end of our own page tables; the +0x007 is >> - * the attribute bits >> + * End condition: we must map up to end >> */ >> - leal (INIT_MAP_BEYOND_END+PTE_IDENT_ATTR)(%edi),%ebp >> + movl $pa(_end) + PTE_IDENT_ATTR, %ebp >> cmpl %ebp,%eax >> jb 10b >> addl $__PAGE_OFFSET, %edi >> @@ -638,6 +623,10 @@ swapper_pg_fixmap: >> .fill 1024,4,0 >> ENTRY(empty_zero_page) >> .fill 4096,1,0 >> + >> +.section ".bss.extra_page_aligned","wa" >> + .align PAGE_SIZE_asm >> + .fill INIT_MAP_SIZE,1,0 >> > > this 4 lines are not needed. you already had RESERVE_BRK for it. > > OK. I've updated the changeset and repushed. J