From: Wolfgang Denk <wd@denx.de>
To: David Updegraff <dave@cray.com>
Cc: linuxppc-embedded@lists.linuxppc.org
Subject: Re: mem= flag behaviour
Date: Tue, 11 Jun 2002 18:34:52 +0200 [thread overview]
Message-ID: <20020611163457.DD91C102F8@denx.denx.de> (raw)
In-Reply-To: Your message of "Tue, 11 Jun 2002 11:15:46 CDT." <3D062232.3010003@cray.com>
Dear David,
in message <3D062232.3010003@cray.com> you wrote:
>
> I'm trying to keep a small trace buffer over re-boots
> of linux from ppcboot, so give a mem=31M flag to linux
> kernel. Yet by the time linux is up, it has overwritten
> that memory anyway.. PPCBOOT is properly leaving it
> be (with PRAM feature) and correct arg. goes to kernel..
Let me guess... you boot with a ramdisk image?
> After 'reboot' from linux, the memory contents of
> the last meg are still valid (in ppcboot) but by the time linux
> is back up, the region has been trashed. Why?
If you use a ramdisk image, you should read the documentation for the
"initrd_high" environment variable in
http://www.denx.de/doc/TQM8xxL/ppcboot.html#PPCBOOT-VARIABLES
(or in the PPCBoot README).
> Help, please. How to prevent linux from talking to
> that memory region during bootup?
Linux does not use the memory beyond what you tell it with "mem=".
Hope this helps...
[BTW: your CD is in the mail.]
Wolfgang Denk
--
Software Engineering: Embedded and Realtime Systems, Embedded Linux
Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Email: wd@denx.de
Machines take me by surprise with great frequency. - Alan Turing
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
prev parent reply other threads:[~2002-06-11 16:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-06-11 13:36 About IDE_DIRECT on PCMCIA port in ppcboot and linux Dross Zhou
2002-06-11 16:15 ` mem= flag behaviour David Updegraff
2002-06-11 16:34 ` Wolfgang Denk [this message]
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