From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Lameter Date: Wed, 04 Apr 2007 23:06:24 +0000 Subject: [PATCH 2/4] x86_64: SPARSE_VIRTUAL 2M page size support Message-Id: <20070404230624.20292.32311.sendpatchset@schroedinger.engr.sgi.com> List-Id: References: <20070404230619.20292.4475.sendpatchset@schroedinger.engr.sgi.com> In-Reply-To: <20070404230619.20292.4475.sendpatchset@schroedinger.engr.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: akpm@linux-foundation.org Cc: linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, Martin Bligh , linux-mm@kvack.org, Andi Kleen , Christoph Lameter , Dave Hansen , KAMEZAWA Hiroyuki x86_64 implement SPARSE_VIRTUAL x86_64 is using 2M page table entries to map its 1-1 kernel space. We implement the virtual memmap also using 2M page table entries. So there is no difference at all to FLATMEM. Both schemes require a page table and a TLB for each 2MB. FLATMEM still references memory since the mem_map pointer itself a variable. SPARSE_VIRTUAL uses a constant for vmemmap. Thus no memory reference. SPARSE_VIRTUAL should be superior to even FLATMEM. With this SPARSEMEM becomes the most efficient way of handling virt_to_page, pfn_to_page and friends for UP, SMP and NUMA on x86_64. Signed-off-by: Christoph Lameter Index: linux-2.6.21-rc5-mm4/include/asm-x86_64/page.h =================================--- linux-2.6.21-rc5-mm4.orig/include/asm-x86_64/page.h 2007-04-03 18:41:06.000000000 -0700 +++ linux-2.6.21-rc5-mm4/include/asm-x86_64/page.h 2007-04-03 18:41:59.000000000 -0700 @@ -128,6 +128,7 @@ extern unsigned long phys_base; VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC) #define __HAVE_ARCH_GATE_AREA 1 +#define vmemmap ((struct page *)0xffffe20000000000UL) #include #include Index: linux-2.6.21-rc5-mm4/Documentation/x86_64/mm.txt =================================--- linux-2.6.21-rc5-mm4.orig/Documentation/x86_64/mm.txt 2007-04-03 18:41:06.000000000 -0700 +++ linux-2.6.21-rc5-mm4/Documentation/x86_64/mm.txt 2007-04-03 18:41:59.000000000 -0700 @@ -9,6 +9,7 @@ ffff800000000000 - ffff80ffffffffff (@ ffff810000000000 - ffffc0ffffffffff (F bits) direct mapping of all phys. memory ffffc10000000000 - ffffc1ffffffffff (@ bits) hole ffffc20000000000 - ffffe1ffffffffff (E bits) vmalloc/ioremap space +ffffe20000000000 - ffffe2ffffffffff (@ bits) virtual memory map ... unused hole ... ffffffff80000000 - ffffffff82800000 (@ MB) kernel text mapping, from phys 0 ... unused hole ... Index: linux-2.6.21-rc5-mm4/arch/x86_64/Kconfig =================================--- linux-2.6.21-rc5-mm4.orig/arch/x86_64/Kconfig 2007-04-03 18:41:06.000000000 -0700 +++ linux-2.6.21-rc5-mm4/arch/x86_64/Kconfig 2007-04-03 18:41:59.000000000 -0700 @@ -392,6 +392,12 @@ config ARCH_SPARSEMEM_ENABLE def_bool y depends on (NUMA || EXPERIMENTAL) +config SPARSE_VIRTUAL + def_bool y + +config ARCH_SUPPORTS_PMD_MAPPING + def_bool y + config ARCH_MEMORY_PROBE def_bool y depends on MEMORY_HOTPLUG