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JEMM386 v5.81 hangs (Users)

posted by CandyMan, 04.05.2022, 16:02

> > In my opinion, this is because JEMM386 does not check whether memory
> size
> > is equal to the XBDA segment:
> > MemW[$413] shl 6 = MemW[$40E]
> > If not, he should refrain from moving the XBDA.
>
> In my opinion it is because AHCI expects some alignment of its structures
> which Jemm cannot easily guarantee, especially if it moves itself into an
> UMB first.
>
> You may try UMBPCI & UMBM, umbm.exe has got an /xbda option - it's "better"
> aligned, because umbm doesn't have to "move itself" ( although I've
> forgotten the details ).
>
> Or perhaps try jemm with option NOHI!
>
> Btw, what is the status of the "dark debugger"? Is that something that you
> created - or at least are involved with? I find it a very interesting
> project.
I added a few lines to the code in INIT.ASM (security is there anything below XBDA) and now it doesn't hang.

if ?MOVEXBDA and ?MOVEXBDAPM
    push ebx
    test bV86Flags,V86F_MOVEXBDA
    jz nomovexbda
    movzx eax,word ptr ds:[@XBDA]   ;does XBDA exist?
    and eax,eax
    jz nomovexbda
  if 1                       
    mov cx,ds:[@MEM_SIZE]
    shl cx,6
    cmp ax,cx
    jnz nomovexbda
  endif
...

I was also able to modify UMBM so that it transfers GRUB4DOS and XBDA data to UMB, thanks to which I have 22KB more conventional memory.

The dark debugger has been completed and so far I have no plans to change anything.

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