Re: Memory Configuration Space

[Gene Morgan <morgan@equator.com>]

Jens Richter wrote:
> 
> Hallo Newsgroup-Reader,
> 
> I do have a question of understanding:
> On reading the base address register for memory and determining, that the
> device requests for 8kByte of mem-space, does the base address which I write
> into the BAR has to be 8k aligned?
> 

Yes.

> The PCI-spec, rev 2.1 says in 6.2.5.1: .. all address spaces are a power of two
> in size and are naturally aligned. Does this mean, if the device requires 8K of
> config space, the BAR must be 8K aligned?
> 

Yes.

> e.g.
> 
> pci memory configuration space @ 0x50000000
> 
> dev 1 req. 4K mem space -> BAR = 0x50000000; next free addr. 0x50001000
> dev 2 req. 4K mem space -> BAR = 0x50001000; next free addr. 0x50002000
> dev 3 req. 16K mem space ->BAR = 0x50002000 or 0x50004000 ?????
> 

0x50004000. 0x50002000 would not work for the 16KB region.

> Best Regards
> Jens
> 
> -------------------------------------------------------->
> Jens Richter              NENTEC Netzwerktechnologie GmbH
> eMail: richter@nentec.de  Killisfeldstrasse 64
> Phone: +49-721-9495-223   D-76227 Karlsruhe/Germany
> Fax:   +49-721-9495-166   http://www.nentec.de