Subject: Re: Bad Mac OS ROM issues
From: David (dsmol@ddv.com)
Date: Thu Jun 01 2000 - 16:04:29 MDT
I should also note that in case anyone's wondering what the Mac does prior
to loading any extensions/cdevs (although _not_ with extensions disabled)
that causes the screen resolution to switch from the initial resolution to
"some other resolution"...
It's reading the "display preferences" file from the preferences folder. I
couldn't figure this out for quite a while. (I removed all extensions, all
control panels, and I was still crashing at boot time when it tried to go
to a resolution > 800x600). I booted with extensions off (which bypasses
reading the preferences apparently also) and removed the Display Prefs and
I was no longer crashing at boot time.
Can someone on the list please clarify what the latest Mac OS ROM file is
and what the easiest place to extract it from is.
I should also add that from the finder "about this macintosh..." screen,
the ROM version reported was 3.2.1 for both the ROM that crashed my
machine horribly when trying resolutions > 800x600 and also for the ROM
that seems to be working fine. I'm wondering if there's something weird
going on in strip_nwrom.
-David
On Thu, 1 Jun 2000, Benjamin Herrenschmidt wrote:
> That's interesting. I did experience similar problems when trying to use
> large resolutions recently with both the 3.7 and 3.8 (MacOS 9.0.4 and
> "Ethernet Update") ROM images. I don't yet know if it's related to the
> ROM image itself or something else. I'm currently running on a different
> machine at 800x600 and it works very well.
>
> The symptom of the problem is the MacOS crashing (freeze) during
> framebuffer access, when re-painting the screen just after the resolution
> switch.
>
> I also noticed, with the latest MOL version, running at 800x600,
> occasional (but very rare) update "misses" (a video page was not
> correctly detected as dirty and so was not updated, causing a couple of
> lines beeing wrong on the display). This happened only once or twice in
> several hours and forcing a screen refresh fixed it.
>
> Samuel, could there still be some kind of race in the video driver or in
> the kernel-side page fault stuff ? The crash at high resolution also
> happened with full-screen video, which doesn't use the page-fault
> mecanism, so I'm not sure those two problems are actually related.
>
> Ben.
>
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