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RE: How to allocate about 64K bytes base memory

From: Feng Shuo
Subject: RE: How to allocate about 64K bytes base memory
Date: Thu, 15 Apr 2004 09:02:04 +0800

I'd love to use HMA, but the UNDI driver can only be installed in base
memory :( below 640K).
And what's even worse, my pxegrub always told me that 639K base memory
is available (by 'displaymem'), but I believe 'FRM' (at 40:13h) is never
more than 590(K). I'm afraid that grub has decided to crash the UNDI
APIs before I do anything :(

Feng Shuo
-----Original Message-----
From: Kai Mosebach [mailto:address@hidden 
Sent: Wednesday, April 14, 2004 10:26 PM
To: 'Feng Shuo'
Subject: AW: How to allocate about 64K bytes base memory

What about the UPPER mem (after the VGA-Memory (VGA is from 640k to 704
I think, so UPPER should begin)) or the HMA (thought you need to play
around with the infamous A20Gate) ?

>From http://www.pcguide.com/ref/ram/umaMap-c.html

Optional Adapter ROM BIOS or RAM UMBs: The blocks of memory from CC000h
to DFFFFh are available for optional use. This memory can be used by
hardware adapters for their ROM code (for example, some network cards,
or SCSI host adapters). Or, the memory can be used as upper memory block
RAM for loading drivers. Usually this memory is referred to in chunks of
16 KB (4000h) but a device does not need to use this much if it does not
need it. This address space is normally empty unless you are using
specialized hardware such as the devices I just mentioned.

Best kai

> -----Ursprüngliche Nachricht-----
> Von: address@hidden [mailto:bug-grub-
> address@hidden Im Auftrag von Feng Shuo
> Gesendet: Mittwoch, 14. April 2004 15:48
> An: address@hidden
> Betreff: How to allocate about 64K bytes base memory
> I’m still working on UNDI now :(
> Most PXE UNDI APIs need 32K-64K bytes base memory to work. Where can I
> allocate them safely?
> I have tried to do this at the high end of the base memory, at the low
> end, and at the 512K-576K (the end of the grub used memory). ----None
> them seems work well with grub in loading kernel or disk I/O :(
> BTW. Dose grub need to work with interrupt enable or disable?
> Feng Shuo
> Email: address@hidden
> Tel:(86)10-62659372ext1003
> Fax:(86)10-62657255
> Postcode:100080
> National Engineering Centre for High Performance Computer
> Institute of Computing Technology,Chinese Academy of Sciences
> 6,Kexueyuan Road South,
> Haidian District, Beijing,China
> _______________________________________________
> Bug-grub mailing list
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