From: 郭劲 <guojin02@tsinghua•org.cn>
To: "Scott Wood" <scottwood@freescale•com>,
"vijay baskar" <cn.vijaibaskar@gdatech•co.in>
Cc: linuxppc-embedded@ozlabs•org
Subject: Re: The question about the high memory support on MPC8360?
Date: Thu, 29 Nov 2007 11:11:50 +0800 [thread overview]
Message-ID: <396305910.05464@tsinghua.org.cn> (raw)
Hi,friends,
I plug in 2GB DDR-1 in my MPC8360 board,there are two DIMM-184 slots,each
DIMM-184 slot hold 1GB.Could you tell me how to let the linux know about those
2GB?
In uboot, I set up each DDR CS to visit 512MB, total 4 CS signal. DDR window
range is 2GB. I think the uboot has passed those DDR parameter to linux.
I once did a test that config the bootargs with mem=512M, then the linux just
only find 512MB, but if I config the mem=2048M, the linux still find about 750MB.
How to make the linux find the total 2GB memory?
>From: Scott Wood <scottwood@freescale•com>
>Reply-To:
>To: vijay baskar <cn.vijaibaskar@gdatech•co.in>
>Subject: Re: The question about the high memory support on MPC8360?
>Date:Wed, 28 Nov 2007 10:57:38 -0600
>
>vijay baskar wrote:
>> Hi, "The kernel also allows hardcoded mapping of IO regions into its
>> virtual address space through the io_block_mapping interface."
>>
>> Can u tell me how this is in current arch/powerpc.
>
>Everything is explicitly ioremapped.
>
>> Also does it mean that whatever be the size of the ram > 768 MB there
>> is not going to be much improvement in performance in kernel space
>> irrespective of invoking CONFIG_HIGHMEM or not?
>
>Well, the kernel can use highmem for cache... I'm not sure what you
>mean by "in kernel space".
>
>> Also do you think this low mem be enough if i have lots of kernel
>> space processes each invoking lots of kmallocs.
>
>That depends on what you mean by "lots". :-)
>
>You'll have 768MB of lowmem, and kmallocs can only use lowmem.
>
>> Will there be bottle necks?? Also what alternative do we have if low
>> mem of 768 MB is not enough??
>
>You'll need to change the user/kernel split, and deal with anything that
>breaks in the process.
>
>Or get a 64-bit chip. :-)
>
>-Scott
>
next reply other threads:[~2007-11-29 3:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-29 3:11 郭劲 [this message]
2007-11-29 7:29 ` The question about the high memory support on MPC8360? vijay baskar
2007-11-29 12:59 ` robert lazarski
2007-11-29 16:09 ` Dale Farnsworth
2007-11-29 19:41 ` Rune Torgersen
-- strict thread matches above, loose matches on Subject: below --
2007-11-26 3:58 郭劲
2007-11-26 6:11 ` vijay baskar
2007-11-26 16:57 ` Scott Wood
2007-11-27 4:27 ` vijay baskar
2007-11-27 17:02 ` Scott Wood
2007-11-28 4:02 ` vijay baskar
2007-11-28 16:57 ` Scott Wood
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