Re: [Freedos-devel] KEYB BUG

[Rugxulo <ru...@gm...>]

Hi,

On Mon, Jun 25, 2012 at 6:24 AM, Tom Ehlert <te...@dr...> wrote:
>
>>    KEYB.EXE 11,446 06-24-12
>
>> leaves, when running, a huge memory hole. at least with only HIMEM
>> loaded. note the HUGE memory hole behind KEYB
>
> the problem is
>
> function MCBAlloc ( para: word ) : word;
> var allocs,f,m: word;
>
>        mov     ah, $58          { set alloc strategy }
>        mov     al, 1
>        xor     bh,bh
>>>>     mov     bl, $41
>        int     $21
>
> using 'best fit' is virtually ALWAYS a bug for a TSR
>
> solution 2) use
>      mov     bl, $82   last fit, try high then low memory
>
> this allocates memory from top, but doesn't create holes.
>
> unfortunately I'm not able to compile this; awaiting the  maintainer
> to fix this bug

Surely a simple binary patch is possible in the meantime. I've not
tested this (yet), but you could try this:

upx -d keyb.exe
hiew keyb.exe (or similar hex editor)
offset 0x3E06 is "mov bl, 0x41"
change offset 0x3E07 from 0x41 to 0x82
run modified version for comparison (keyb.exe /blah ...)