linux-kernel - Re: Testing RAM from userspace / question about memmap= arguments

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Message-ID: <20071221125812.GA4052@ucw.cz>
Date:	Fri, 21 Dec 2007 12:58:12 +0000
From:	Pavel Machek <pavel@....cz>
To:	Matthew Bloch <matthew@...emark.co.uk>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Testing RAM from userspace / question about memmap= arguments

On Tue 2007-12-18 17:06:24, Matthew Bloch wrote:
> Hi - I'm trying to come up with a way of thoroughly testing every byte
> of RAM from within Linux on amd64 (so that it can be automated better
> than using memtest86+), and came up with an idea which I'm not sure is
> supported or practical.
> 
> The obvious problem with testing memory from user space is that you
> can't mlock all of it, so the best you can do is about three quarters,
> and hope that the rest of the memory is okay.
> 
> In order to test all of the memory, I'd like to run the user-space
> memtester over two boots of the kernel.
> 
> Say we have a 1024MB machine, the first boot I'd not specify any
> arguments and assume the kernel would start at the bottom of physical
> memory and work its way up, so that the kernel & working userspace would
> live at the bottom, and the rest would be testable from space.
> 
> On the second boot, could I then specify:
> 
> memmap=exact memmap=512M@...M memmap=512M@0

Actually, with kexec, you can probably doing without reboot.

							Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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