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Re: why scrub memory?
- From: Mark Salter <msalter at redhat dot com>
- To: aarichar at cisco dot com
- Cc: ecos-discuss at sources dot redhat dot com
- Date: Fri, 20 Jun 2003 15:38:43 -0400 (EDT)
- Subject: Re: [ECOS] why scrub memory?
- References: <200306201405.45016.aarichar@cisco.com>
>>>>> Aaron Richardson writes:
> I see on several platforms (including the one that I am working on) that
> memory scrubbing is occuring. Why is this done and can I remove it? I am
> tired of waiting the time for this occur. I have 256 MB of memory right now,
> but plan on having much more in the future.
When the ECC memory is first powered on, it must be written to
before it is read. This syncs the ECC code bits with the data
bits. The simplest approach is taken and all of memory is
scrubbed before any is used. If the application that RedBoot
boots (or the standalone eCos app) is not going to muck with
the MMU, then the HAL could be enhanced to defer scrubbing a
given memory page until that page is first touched. But only
if that's not a performance problem for the app.
--Mark
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