Hi!
23-Сен-2004 18:49 [EMAIL PROTECTED] (tom ehlert) wrote to Aitor Santamarэa
Merino <[EMAIL PROTECTED]>:
>> (3) XMS UMB functions are not supported. I just wonder if MS-HIMEM
>> implements them: now that HIMEM is quite machine specific, perhaps this
>> is the way Microsoft implement their "UMBPCI" (just a reflection)
te> it's not in - neither in MS HIMEM.
te> but the himem call mechanism is intended to be hooked (by emm386,
te> umbpci or similar)
There is weel documented way, how to built itself into chain of XMS
providers. EMM386 (or other such program) does this for WUMB related
functions. About "XMM chain" you may read in XMS specififcations. For
example: http://burks.brighton.ac.uk/burks/pcinfo/progdocs/xms30.htm
>> (4) Finally, I am unable to understand the whole process behind making a
>> mixed SYS/EXE driver, can someone clarify about this?
>> - HIMEM64 starts with a device driver header
>> - HIMEM.EXE actually starts with "MZ", so it can be open as an
>> executable. How is that the kernel can open it as a driver, if it
>> doesn't start with the device driver header?
Kernel always _loads_ device (DEVICE=) same, as plain executable (ie.
for files with MZ header performed relocations resolving). Only after this
for DEVICE= kernel uses start of loaded image as device driver header.
The more so, device driver may be also .COM compliant: first four bytes
of driver header is a FAR address, where you may put JMP instruction to go
around driver header/code into "program" code.
>> - Who calls ASMSTART_EXE?
te> if the kernel loads a device= , it uses the device driver header.
te> if the kernel loads an executable, it looks into the MZ-header to find
te> the start address (which happens to be ASMSTART_EXE)
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