On Wed, Oct 03, 2012 at 09:45:51AM -0400, Dave Anderson wrote: > > Right -- it looks to be a bug, presuming that ARM is using 1MB pages > for the unity-mapped region: > > crash> vtop c0000000 | grep PAGE: > PAGE: 11000 (1MB) > crash> vtop c0100000 | grep PAGE: > PAGE: 11000 (1MB) > crash> vtop c0200000 | grep PAGE: > PAGE: 211000 (1MB) > crash> vtop c0300000 | grep PAGE: > PAGE: 211000 (1MB) > crash> vtop c0400000 | grep PAGE: > PAGE: 411000 (1MB) > crash> vtop c0500000 | grep PAGE: > PAGE: 411000 (1MB) > crash> The unity-mapped region is mapped using 1MB pages. However, we actually have (when using the Linux ARM 2-level translation scheme): see arch/arm/include/asm/pgtable-2level.h: #define PMD_SHIFT 21 #define PGDIR_SHIFT 21 #define PTRS_PER_PGD 2048 So we have 2048 entries in a PGD instead of 4096 making a PGD entry an array of "two pointers". Anyway as you and Paawan suggested it looks like a bug - we always use the first entry instead of the second given that bit 20 is set in the virtual address. Paawan, your fix looks sane to me but can you add a small comment describing why this is done? -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
