| [hatari-devel] Regression in Hatari w.r.t. "ST High" video mode |
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- To: hatari-devel@xxxxxxxxxxxxxxxxxxx
- Subject: [hatari-devel] Regression in Hatari w.r.t. "ST High" video mode
- From: Christian Zietz <czietz@xxxxxxx>
- Date: Tue, 14 Jun 2022 13:05:06 +0200
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Hello,
lately, I compiled Hatari for Linux on AArch64, which I haven't done
before. There, I noticed that ST High (monochrome) video mode would not
work. The screen would just stay white except for the status bar; while
the floppy access indicator showed that otherwise the emulated ST was in
fact running. On the same system, ST High works when compiling Hatari
2.3.1 instead.
Bisecting lead me to the following commit as cause for the regression:
"Add sanity checks to avoid accesses beyond the end of the ST-RAM":
https://git.tuxfamily.org/hatari/hatari.git/commit/?id=c3875fc8bf3148c376262a71966fd4bbcd54ff22.
I added some debug printfs to see the variables which are involved in
the check that was added by this commit:
fvram, nextline, (Uint16 *)&STRam[STRamEnd]
DEBUG: 0x7f94b8e010 28 0x7f87c70010
DEBUG: 0x7f94b01010 28 0x7f87c70010
As you can see, the "fvram" is outside the ST RAM area, causing the
check to fail and, therefore, the screen to be drawn white. I did not
have time to fully debug this. But I think this happens because for mono
mode a separately allocated screen buffer pSTScreen is used:
https://git.tuxfamily.org/hatari/hatari.git/tree/src/screen.c#n735
https://git.tuxfamily.org/hatari/hatari.git/tree/src/screen.c#n190
If that memory allocation by chance happens to be *below* the ST RAM,
the check passes; otherwise (like on my AAarch64 system), it fails.
Imho, this needs to be fixed before a 2.4 release.
Regards
Christian
--
Christian Zietz - CHZ-Soft - czietz@xxxxxxx
WWW: https://www.chzsoft.de/
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