[PATCH] PPC64: Don't try to claim memory from OF at 1GB mark
Some RS64-based machines (p620, F80, others) have problems with firmware
returning 0xdeadbeef instead of failure to allocations that end at the
1GB mark.
We have two options:
1. Detect the undocumented 0xdeadbeef return value and interpret it as
a failure.
2. Avoid allocating that high.
(2) is really the cleaner solution here. 768MB is plenty of room so use
that as the max alloc_top instead of 1GB.
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/ppc64/kernel/prom_init.c b/arch/ppc64/kernel/prom_init.c
index adcf972..122283a 100644
--- a/arch/ppc64/kernel/prom_init.c
+++ b/arch/ppc64/kernel/prom_init.c
@@ -892,7 +892,10 @@
if ( RELOC(of_platform) == PLATFORM_PSERIES_LPAR )
RELOC(alloc_top) = RELOC(rmo_top);
else
- RELOC(alloc_top) = RELOC(rmo_top) = min(0x40000000ul, RELOC(ram_top));
+ /* Some RS64 machines have buggy firmware where claims up at 1GB
+ * fails. Cap at 768MB as a workaround. Still plenty of room.
+ */
+ RELOC(alloc_top) = RELOC(rmo_top) = min(0x30000000ul, RELOC(ram_top));
prom_printf("memory layout at init:\n");
prom_printf(" memory_limit : %x (16 MB aligned)\n", RELOC(prom_memory_limit));