From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from buildserver.ru.mvista.com (unknown [85.21.88.6]) by ozlabs.org (Postfix) with ESMTP id 6267F47502 for ; Thu, 18 Dec 2008 07:09:11 +1100 (EST) Date: Wed, 17 Dec 2008 23:09:10 +0300 From: Anton Vorontsov To: Paul Mackerras Subject: [PATCH 4/7] powerpc/32: Allow to ioremap RAM addresses for kdump kernel Message-ID: <20081217200910.GD4624@oksana.dev.rtsoft.ru> References: <20081217200610.GA31887@oksana.dev.rtsoft.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=windows-1251 In-Reply-To: <20081217200610.GA31887@oksana.dev.rtsoft.ru> Cc: Milton Miller , linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , While for debugging it is good to catch bogus users of ioremap, though for kdump support it is more convenient to use ioremap for copy_oldmem_page() (exactly as we do for PPC64 currently). Note that copy_oldmem_page() calls __ioremap with flags set to '0', so it should be safe with the regard to the caches. The other option is to use kmap_atomic_pfn()[1], but it will not work for kernels compiled without HIGHMEM. That is, on a board with 256MB RAM and crashkernel=64M@32M case, the !HIGHMEM capturing kernel maps 0-96M range, which does not include all the memory needed to capture the dump. And, obviously, accessing anything upper than 96M will cause faults. [1] http://ozlabs.org/pipermail/linuxppc-dev/2007-November/046747.html Signed-off-by: Anton Vorontsov --- arch/powerpc/mm/pgtable_32.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c index 3414724..cd56097 100644 --- a/arch/powerpc/mm/pgtable_32.c +++ b/arch/powerpc/mm/pgtable_32.c @@ -173,6 +173,7 @@ __ioremap(phys_addr_t addr, unsigned long size, unsigned long flags) if (p < 16*1024*1024) p += _ISA_MEM_BASE; +#ifndef CONFIG_CRASH_DUMP /* * Don't allow anybody to remap normal RAM that we're using. * mem_init() sets high_memory so only do the check after that. @@ -182,6 +183,7 @@ __ioremap(phys_addr_t addr, unsigned long size, unsigned long flags) (unsigned long long)p, __builtin_return_address(0)); return NULL; } +#endif if (size == 0) return NULL; -- 1.5.6.5