Re: [BUG] 2.6.26-rc1 lost half the RAM on UltraSPARC 5

David Miller writes:
From: Mikael Pettersson <mikpe@xxxxxxxx>
Date: Tue, 13 May 2008 21:31:19 +0200

Ok, Mikael, I think I figured out this bug:

Found ramdisk at physical address 0x10800000, size 3683665
lmb_dump_all:
memory.cnt = 0x4
memory.size = 0xff40000
memory.region[0x0].base = 0x0
.size = 0x8000000
memory.region[0x1].base = 0x10000000
.size = 0x7efe000
memory.region[0x2].base = 0x17f00000
.size = 0x3a000
memory.region[0x3].base = 0x17f3e000
.size = 0x8000
reserved.cnt = 0x2
reserved.size = 0x0
reserved.region[0x0].base = 0x10000000
.size = 0x35bf60
reserved.region[0x1].base = 0x10800000
.size = 0x10b83551

From the very beginning your higher RAM is gone.
It's correct that some memory should be reserved,
for the ramdisk, but not 128MB :-)

The ramdisk is just under 4MB in size, so something is fishy here.

And indeed, I'm reserving the wrong length. Please try this
patch:

sparc64: Fix lmb_reserve() args in find_ramdisk().

This fixes the missing ram regression reported by
Mikael Pettersson <mikpe@xxxxxxxx>, much thanks for
all of this help in diagnosing this.

The second argument to lmb_reserve() is a size,
not an end address bounds.

Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
---
arch/sparc64/mm/init.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/sparc64/mm/init.c b/arch/sparc64/mm/init.c
index a9828d7..3c7b947 100644
--- a/arch/sparc64/mm/init.c
+++ b/arch/sparc64/mm/init.c
@@ -768,7 +768,7 @@ static void __init find_ramdisk(unsigned long phys_base)
initrd_start = ramdisk_image;
initrd_end = ramdisk_image + sparc_ramdisk_size;

- lmb_reserve(initrd_start, initrd_end);
+ lmb_reserve(initrd_start, sparc_ramdisk_size);

initrd_start += PAGE_OFFSET;
initrd_end += PAGE_OFFSET;
--
1.5.5.1.57.g5909c


Thanks Dave. As the dmesg diff below shows, this patch fixed
my lost RAM issue. I actually have about 8KB more available
now than I had with 2.6.25.

Tested-by: Mikael Pettersson <mikpe@xxxxxxxx>

--- dmesg-2.6.26-rc2-a 2008-05-15 16:12:39.000000000 +0200
+++ dmesg-2.6.26-rc2-b 2008-05-15 16:18:37.000000000 +0200
@@ -1,14 +1,14 @@
PROMLIB: Sun IEEE Boot Prom 'OBP 3.25.3 2000/06/29 14:12'
PROMLIB: Root node compatible:
-Linux version 2.6.26-rc2 (mikpe@sparge) (gcc version 4.2.3) #1 Wed May 14 22:27:26 CEST 2008
+Linux version 2.6.26-rc2 (mikpe@sparge) (gcc version 4.2.3) #2 Thu May 15 16:14:24 CEST 2008
console [earlyprom0] enabled
ARCH: SUN4U
Ethernet address: 08:00:20:fd:ec:1f
-Found ramdisk at physical address 0x10800000, size 3780573
+Found ramdisk at physical address 0x10800000, size 3780646
Kernel: Using 1 locked TLB entries for main kernel image.
Remapping the kernel... done.
OF stdout device is: /pci@1f,0/pci@1,1/SUNW,m64B@2
-PROM: Built device tree with 42146 bytes of memory.
+PROM: Built device tree with 42148 bytes of memory.
bootmem_init_nonnuma()
Top of RAM: 0x17f46000, Total RAM: 0xff42000
Memory hole size: 128MB
@@ -25,8 +25,12 @@
MATCH reserving range [7ffe000:8000000]
reserve_range_in_node(nid[0],start[10000000],end[1030ed28]
MATCH reserving range [10000000:1030ed28]
- reserve_range_in_node(nid[0],start[107eb3c0],end[2139afdd]
- MATCH reserving range [107eb3c0:2139afdd]
+ reserve_range_in_node(nid[0],start[10800000],end[10b9b026]
+ MATCH reserving range [10800000:10b9b026]
+ reserve_range_in_node(nid[0],start[17f2f3c0],end[17f3c000]
+ MATCH reserving range [17f2f3c0:17f3c000]
+ reserve_range_in_node(nid[0],start[17f3e000],end[17f46000]
+ MATCH reserving range [17f3e000:17f46000]
sparse_memory_present_with_active_regions(0)
[0000000200000000-fffff80000400000] page_structs=131072 node=0 entry=0/0
[0000000200000000-fffff80000800000] page_structs=131072 node=0 entry=1/0
@@ -53,9 +57,9 @@
console handover: boot [earlyprom0] -> real [tty0]
Dentry cache hash table entries: 32768 (order: 5, 262144 bytes)
Inode-cache hash table entries: 16384 (order: 4, 131072 bytes)
-Memory: 127016k available (1920k kernel code, 744k data, 152k init) [fffff80000000000,0000000017f46000]
+Memory: 245448k available (1920k kernel code, 744k data, 152k init) [fffff80000000000,0000000017f46000]
...
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