Re: BIOS and BARs

["Bender, Bernhard" <br@elsa.de>]

Anne,

You should restrict you I/O request to the bare minimum you need. 4Kbyte 
is far too much, it may not even be allowed by the spec.

The maximum you are likely to get is 256 Bytes, but better use only 32 or 
less Bytes (if possible).

Restricting the memory mapped BAR to below 1MB is not a good idea either. 
The BAR should be free to move anywhere in the 4GB space unless there are 
very strong reasons to have it in the DOS/PS adapter space. This then may 
not work an all PCs and will fail on most non-PC systems.

Bernhard Bender
---
Group Manager Core Technology   ELSA Computer Graphics

ELSA GmbH             		Email: br@elsa.de
Sonnenweg 11                    Fax  : +49 (2405) 450 100
D-52 070 Aachen, Germany        WWW  : http://www.elsa.de


***  Original Message Follows  ***

I am now testing a PCI board under DOS. Only two base address registers 
are 
set. BAR 0 requires 4kbytes of I/O space and BAR1 requires 4kbytes of 
memory, under 1Mbyte to be seen by dos.
At boot, the PC (the BIOS) does not give any warning message or error 
massage but when I look at the content of my BAR1 I see that it did not 
implement it below 1 Mbyte but on top of the 4Gbytes, so I cannot access 
my 
board under DOS.
Is it normal that the BIOS gives no warning message when it does not 
respect 
the requirements given ?
Is it normal that a PC with nothing else than this board (with 2 BARs 
only) 
is not able to satisfy these requirements (4kbytes of memory)?

Thanks

Anne

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***  End of Original Message  ***
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