[LinuxBIOS] does reinitializing memory controller destroy all the data in ram?

RusH citizenr at gmail.com
Mon Jun 11 06:58:53 CEST 2007

On 6/10/07, Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net> wrote:
> On 10.06.2007 06:40, RusH wrote:
> >
> >  Im asking about reinitialization because I want to implement it in
> > Memtest (memtest.org). I want to be able to setup memory controller the
> > way I like and continue the test. Memtest is big (>100KB) and Im
> > afraid it wont fit in cache so i need some real ram. That's where the
> > 'jump to CAR, reinitialize controller, jump back to ram' idea comes
> > from. Is it doable?
> Why not run Memtest from graphics card RAM? A few years ago, graphics
> card RAM was really low quality, so periodic checksumming of any
> software running there might be necessary.

Date: Wed, 30 May 2007 18:57:44 +0200
From: RusH <citizenr at gmail.com>
To: linuxbios at linuxbios.org
Subject: using Graphics card ram as actual ram?
Message-ID: <3df49b7b0705300957l3d063c50p404ed2cb07b8bd9 at mail.gmail.com>

so yes, i was thinking about it :)

> > Does reinitializing memory controller er destroy all the data in ram?
> Depends. Some embedded systems (like the OLPC laptop) put memory
> into self-refresh for suspend-to-RAM and reinitialize the memory
> controller on resume without losing any contents. However, I
> wouldn't count on that for any recent non-embedded x86 system.

What about AMD64 controller? I know I can change a lot of timings on
it, but changing tCAS is not possible without reinitializing, that's
why I want to be able to reinitialize on the fly.

I read somewhere that reinitializing (memory allready set up earlier)
without touching the mappings would be ok, but I want to be sure
before starting coding (easier to ask than sit on it a good week and
wonder why it doesnt work).

I guess I'll have to check for myself. All I got now is two boards
with KT133 chipset, and that doesnt look to be supported (but
PLE133/CLE266 are similar, so maybe that code will do).

Who logs in to gdm? Not I, said the duck.

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