Re: kdump broken on 2.6.37-rc4

From: H. Peter Anvin
Date: Thu Dec 16 2010 - 20:51:52 EST


Can whomever has a test case for this please test the attached test patch?

-hpa

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 23f315c..325c052 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -355,7 +355,7 @@ asmlinkage void decompress_kernel(void *rmode, memptr heap,
if (heap > 0x3fffffffffffUL)
error("Destination address too large");
#else
- if (heap > ((-__PAGE_OFFSET-(512<<20)-1) & 0x7fffffff))
+ if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
error("Destination address too large");
#endif
#ifndef CONFIG_RELOCATABLE
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index bcece91..d7cdf5b 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -60,16 +60,18 @@
#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
#endif

+/* Number of possible pages in the lowmem region */
+LOWMEM_PAGES = (((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT)
+
/* Enough space to fit pagetables for the low memory linear map */
-MAPPING_BEYOND_END = \
- PAGE_TABLE_SIZE(((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT) << PAGE_SHIFT
+MAPPING_BEYOND_END = PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT

/*
* Worst-case size of the kernel mapping we need to make:
- * the worst-case size of the kernel itself, plus the extra we need
- * to map for the linear map.
+ * a relocatable kernel can live anywhere in lowmem, so we need to be able
+ * to map all of lowmem.
*/
-KERNEL_PAGES = (KERNEL_IMAGE_SIZE + MAPPING_BEYOND_END)>>PAGE_SHIFT
+KERNEL_PAGES = LOWMEM_PAGES

INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE_asm
RESERVE_BRK(pagetables, INIT_MAP_SIZE)