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Post by nimbus on Jul 22, 2018 19:50:34 GMT 1
When trying to run the flat assembler, DOS version (FASM.EXE) it crashes immediately, yields the above message in a windows error box, and it aborts vDOS (64 bit) instantly. This is with - or without - first running the DPMI server, CWSDPMI, that FASM relies upon.
Any hint of why this is happening and how to fix the issue if possible ?
I have not investigated in depth, but by the by, I'm finding the vDOS by itself is providing EMS, apparently EMS 3.2 *only*. That might be incompatible with the CWSDPMI :=(
Can the built in EMS 3.2 "board" be removed from vDOS ?
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Post by Jos on Jul 22, 2018 21:32:37 GMT 1
The address/value of the CR3 register must be 4K page aligned, so vDos exits with this error if a program tries to write a non-aligned value to it. EMS memory is always provided, only in previous versions you could turn this off.
FASM is also available as a genuine Windows program, why then run it on an emulated PC/DOS Eventually you could try DOSBox.
Jos
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Post by nimbus on Jul 22, 2018 22:22:44 GMT 1
Hi Jos ! > The address/value of the CR3 register must be 4K page aligned, so vDos exits with this error if a program tries to write a non-aligned value to it. Sure, but why does this condition happen in vDOS ? It never happens in DOS running on real "metal".
>FASM is also available as a genuine Windows program, why then run it on an emulated PC/DOS? - However isn't vDOS supposed to run serious DOS programs, such as FASM ?
> Eventually you could try DOSBox. - Isn't DOSBox, precisely, supposed to be for running GAMES (as opposed to "serious" DOS programs. Cf. previous point ;=)
Anyway I'm just reporting what I found doing casual tests. Never mind if you're not interested in digging deep inside the particular problem re FASM. Still it raises the question , does CWSDPMI-extended programs (other than FASM then) usually run well or at all in vDOS ? What about other "extenders" ? HXDOS ?
(Edited, to add) : re. DOSBOX, precisely, the combo : CWSDPMI + FASM was reported to work on it, by a person named Rugxulo writing to some DOS-oriented news group a couple days ago. I don't have DOSbox myself, but generally I would trust Mr Rugxulo who is an active tester of FreeDOS and all DOS things in general. [later edited:] I've just confirmed CWSDPMI (and FASM) run fine in a "vanilla" DOSBOX, this seems to point to some specific bug or regression in the current vDOS ...
Nim'
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Post by Jos on Jul 23, 2018 7:13:15 GMT 1
Perhaps real CPU’s ignore the offset if found in the address. vDos is intended to run serious programs, though end-user programs that survived and still being used. It doesn’t emulate the PC hardware to a level like DOSBox does.
Don’t know about CWSDPMI or HXDOS extended programs still in use. Only Phar Lap (FoxProX) and DOS/16M (several) that are supported.
Jos
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Post by nimbus on Jul 23, 2018 11:19:53 GMT 1
> Perhaps real CPU’s ignore the offset if found in the address. - Indeed ! Not "perhaps" ° ! If vDOS doesn't, it is clearly a "feature" (== bug :=) in vDOS CPU emulation :=(
° From Intel's official manual : CR3 — Contains the physical address of the base of the paging-structure hierarchy and two flags (PCD and PWT). Only the most-significant bits (less the lower 12 bits) of the base address are specified... the lower 12 bits of the address are assumed to be 0. °° In addition, note that since the 80486 (!) some of those 12 lowest CR3 bits ARE in use by the processor (PCD, PWT, for page-level cache control... maybe more on newer X86-64 architecture). For vDOS emulation purposes you MUST ignore those bits. Absolutely.
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Post by Jos on Jul 23, 2018 14:25:50 GMT 1
I’ll remove the test in the next version.
Jos
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Post by nimbus on Jul 23, 2018 15:31:17 GMT 1
I’ll remove the test in the next version. Thx ! Is there already an estimated date of arrival for "next" ?
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Post by Jos on Jul 23, 2018 17:19:27 GMT 1
Would be first half next year.
Jos
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Post by nimbus on Jul 24, 2018 0:20:41 GMT 1
Would be first half next year. Jos Oh ! Wait till the next year to have an inappropriate check removed ? You must be kidding :=) Well, uh, meanwhile, I'm going to cling with DOSBOX - that does the job. Good luck, Jos ! -- Nim'
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