From 01695a9687e5a8d78589605037cc7828a5b67ac9 Mon Sep 17 00:00:00 2001 From: Anton Vorontsov Date: Wed, 17 Dec 2008 10:09:10 +0000 Subject: [PATCH] powerpc/32: Allow __ioremap on RAM addresses for kdump kernel 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 Signed-off-by: Paul Mackerras --- arch/powerpc/mm/pgtable_32.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c index 34147244013..cd5609759d4 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; -- 2.41.1