Hello, RM:
I do some experiments with 2GB RAM on Fuloong Box。
The preliminary conclusions is:
1. Fuloong can't support 2GB RAM with 2 Ranks(up to now, only one
special model works fine)
2. Fuloong can support some 2GB RAM with 1 Rank.(but no warranty
about the stablility)
The 2.6.38 kernel may need little change to support 2GB RAM, which is:
--- a/arch/mips/loongson/common/pci.c
+++ b/arch/mips/loongson/common/pci.c
@@ -54,7 +54,7 @@ static void __init setup_pcimap(void)
*/
LOONGSON_PCIBASE0 = 0x80000000ul; /* base: 2G -> mmap: 0M */
/* size: 256M, burst transmission, pre-fetch enable, 64bit */
*- LOONGSON_PCI_HIT0_SEL_L = 0xc000000cul;
+ LOONGSON_PCI_HIT0_SEL_L = 0x8000000cul;*
LOONGSON_PCI_HIT0_SEL_H = 0xfffffffful;
LOONGSON_PCI_HIT1_SEL_L = 0x00000006ul; /* set this BAR as
invalid */
LOONGSON_PCI_HIT1_SEL_H = 0x00000000ul;
This new code expand DMA range from 1GB to 2GB.
After communication with our layout engineer and some experts about this
issue,
I 'm sure the root cause has relation to layout design and ddr2
controller configuration.
They have fix these problem since 2009, but Fuloong&Yeeloong is designed
earlier.
Only adjust DDR2 parameters can't fix this:-[ .
Sorry for this limit.
于 2011年04月24日 21:25, Roman Mamedov 写道:
Hello,
I am continuing my experiments with pushing the limits of installed RAM size on
Fuloong/Yeeloong :)
Now I got a 2GB DDR2-800 stick from Hynix, it is a dual-side dual-rank module:
http://www.nix.ru/include/view-photo.html?good_id=87993&pid=2258
With it installed, the Fuloong does not boot with a very strange symptom:
it looks like the kernel can't read anything from the HDD(SSD). The error is
"sda: unknown partition table", so no "/dev/sda2" is found, and the root can't
be mounted: http://romanrm.ru/pics/2011/2011-04-24-fuloong-2gb-boot.jpg
The only way I can boot up with this 2GB RAM stick, is if I first go to the
PMON, enter "set -t highmemsize 768", then load and boot the kernel. That way
it boots up and then works perfectly fine, but of course only 1 GB of RAM is
visible to the kernel.
My guess is that RAM areas are not being set up properly by either PMON or the
kernel with more than 1GB of RAM, and specifically here the DMA reads from the
IDE controller can not be performed correctly.
The PMON version is LM6004-1.3.6, kernels tried are 2.6.38.2 and 2.6.38.3.
--
Xiang Yu (Software Department)
Tel : 0512-52308631
Jiangsu Lemote Technology Corporation Limited
Menglan, Yushan, Changshu City, Jiangsu Province, China
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