[POWERPC] kdump: Reserve the existing TCE mappings left by the first kernel
During kdump boot, noticed some machines checkstop on dma protection
fault for ongoing DMA left in the first kernel. Instead of initializing
TCE entries in iommu_init() for the kdump boot, this patch fixes this
issue by walking through the each TCE table and checks whether the
entries are in use by the first kernel. If so, reserve those entries by
setting the corresponding bit in tbl->it_map such that these entries
will not be available for the kdump boot.
However it could be possible that all TCE entries might be used up due
to the driver bug that does continuous mapping. My observation is around
1700 TCE entries are used on some systems (Ex: P4) at some point of
time during kdump boot and saving dump (either write into the disk or
sending to remote machine). Hence, this patch will make sure that
minimum of 2048 entries will be available such that kdump boot could be
successful in some cases.
Signed-off-by: Haren Myneni <haren@us.ibm.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/include/asm-powerpc/kdump.h b/include/asm-powerpc/kdump.h
index 5a5c3b5..dc1574c 100644
--- a/include/asm-powerpc/kdump.h
+++ b/include/asm-powerpc/kdump.h
@@ -15,6 +15,8 @@
#define KDUMP_TRAMPOLINE_START 0x0100
#define KDUMP_TRAMPOLINE_END 0x3000
+#define KDUMP_MIN_TCE_ENTRIES 2048
+
#else /* !CONFIG_CRASH_DUMP */
#define PHYSICAL_START 0x0