DOS session inside Windows 98 hangs when using the dynamic_x86 core

[Diatonator]

Describe the bug
When something requires a DOS session inside Windows 98 SE the OS hangs.
If just running it from the Start menu - the same result.
I could try Ctrl-Alt-Del to de-hang the system, but the app which uses the DOS mode most likely won't work.

To Reproduce
Steps to reproduce the behavior:

Expected behavior
On a normal core the DOS session worked most of the time I tried it.

Screenshots
The screen just freezes and the mouse pointer too.

Environment (please complete the following information):

• Windows x64
• 0.83.12 with dynamic_x86 core
• Used configuration: win98.zip

Additional context
I seen some discussion here but was unable to find the exact issue on the tracker, thus I created this one

[Wengier]

This is indeed a known issue as pointed out by @joncampbell123 earlier. @koolkdev may want to take a look at it when he has time.

[CyberTacoX]

Bumping this, as the issue still happens, it also affects any Windows program that opens a dos window at all (launchers, patch extractors, etc), and the host CPU savings for switching the cpu core to dynamic_x86 are tremendous. Please give this another look if you could, it would be very appreciated. :-)

[maron2000]

It didn't hang on Windows x64 SDL1.

[joncampbell123]

It is possible that the recent fixes to VGA rendering code fixed the issue by not issuing reads per scanline in case of JEGA/DBCS text modes. I was seeing instability in a DOS VM under Windows 3.1 until I split the JEGA/DBCS case out to another function. Can you confirm that if you compile the latest commit, it no longer occurs?

[CyberTacoX]

I'd be happy to test. Were those VGA fixes incorporated into the latest release, 0.84.0 (05-31-2022)?

[Diatonator]

I downloaded 0.84.1 and the hanging is still there.
I didn't change the config (P1 MMX, dynamic core).