Subject: Re: user mapping pci memory
To: Matthias Drochner <>
From: Matt Thomas <>
List: tech-kern
Date: 03/11/1997 09:32:58
In  <En9HKC26LgUE5gC_hG@zelux6> , you wrote:

> There is another problem with the mmap() return value which
> is hurting me from time to time: (on i386)
> I have a PCI device with a 2k region which I'd like to access from
> user space. Sometimes this area is physically mapped 4k-aligned,
> sometimes not, depending on BIOS version and resource usage in
> the machine. There is no way to tell the user application the actual
> base address (I use an additional ioctl which is ugly).

I don't believe that is possible.  A 2k PCI BAR *must* start on a 
2K boundary because of the BARs work.  There is no possible way for
it to cross a page boundary. 
Matt Thomas               Internet:
3am Software Foundry      WWW URL:
Westford, MA              Disclaimer: I disavow all knowledge of this message