[PATCH] i386: export memory more than 4G through /proc/iomem

Currently /proc/iomem exports physical memory also apart from io device
memory.  But on i386, it truncates any memory more than 4GB.  This leads to
problems for kexec/kdump.

Kexec reads /proc/iomem to determine the system memory layout and prepares a
memory map based on that and passes it to the kernel being kexeced.  Given the
fact that memory more than 4GB has been truncated, new kernel never gets to
see and use that memory.

Kdump also reads /proc/iomem to determine the physical memory layout of the
system and encodes this informaiton in ELF headers.  After a crash new kernel
parses these ELF headers being used by previous kernel and vmcore is prepared
accordingly.  As memory more than 4GB has been truncated, kdump never sees
that memory and never prepares ELF headers for it.  Hence vmcore is truncated
and limited to 4GB even if there is more physical memory in the system.

This patch exports memory more than 4GB through /proc/iomem on i386.

Cc: Maneesh Soni <maneesh@in.ibm.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c
index 4a65040cc624..6712f0d2eb37 100644
--- a/arch/i386/kernel/setup.c
+++ b/arch/i386/kernel/setup.c
@@ -1314,8 +1314,10 @@ legacy_init_iomem_resources(struct resource *code_resource, struct resource *dat
         probe_roms();
         for (i = 0; i < e820.nr_map; i++) {
                 struct resource *res;
+#ifndef CONFIG_RESOURCES_64BIT
                 if (e820.map[i].addr + e820.map[i].size > 0x100000000ULL)
                         continue;
+#endif
                 res = kzalloc(sizeof(struct resource), GFP_ATOMIC);
                 switch (e820.map[i].type) {
                 case E820_RAM:  res->name = "System RAM"; break;