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Date: Tue, 22 Mar 2011 18:45:54 -0400
From: Ed Maste <emaste@freebsd.org>
To: John Baldwin <jhb@freebsd.org>
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Cc: "Bjoern A. Zeeb" <bz@freebsd.org>, freebsd-arch@freebsd.org
Subject: Re: kernel memory checks on boot vs. boot time
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On Tue, Mar 22, 2011 at 03:51:13PM -0400, John Baldwin wrote:

> Do other platforms bother with these sorts of memory tests?  If not I'd vote 
> to just drop it.  I think this mattered more when you didn't have things like 
> SMAP (so you had to guess at where memory ended sometimes).  Also, modern 
> server class x86 machines generally support ECC RAM which will trigger a 
> machine check if there is a problem.  I doubt that the early checks are 
> catching anything even for the non-ECC case.

In the common case at work we want this off to reduce boot time.  The
desire for a tunable though that can add extended memory tests is to be
able to use the FreeBSD startup code as a replacement for memtest86+,
for a couple of reasons:

- FreeBSD's serial console output is more easily parsed by automated
  tools
- Memtest86+ appears to be limited to 64GB of RAM at the moment
- Memtest86+ lacks support for the Tylersburg architecture last I looked

-Ed