Re: SCSI / PCI

On 25-Jun-98 Andy Valencia wrote:
> [Brian J Swetland <swetland@frotz.net> writes:]
>
>>Is PCI support in the works at all? I was about to take a crack at
>>porting my BeOS BusLogic BT-9x8 driver (BeOS also uses CAM, making it
>>a pretty simple task), and realized that I need to be able to detect
>>and potentially configure the PCI card.
>
> There was some PCI work quite a while back, which got far enough to map in
> the card and run some of its code. I recall that there was a real problem
> that the only rules for what BIOS-type code was allowed to do was basically
> "if it works for Windoze...". The most interesting work was probably:
>
> http://www.zendo.com/vsta/mail/10/0009.html
>
> Although PCI pops up here and there throughout the mail archives.

Yeah, I was forced to stop working on that approach because it broke completely
when I changed motherboards/bioses. The BIOS32 mechanism which is supposed to
allow a 32-bit kernel make use of BIOS code is flawed, because there's no way
of telling what memory it wants access to, so you can't do the appropriate
mmaps. There's also the secondary problem that you can't identity map all
parts of the physical address space. I also needed to change the mmap()
syscall itself to allow the use of MAP_FIXED and MAP_PHYS together, but I
haven't looked at recent kernels to see if this is still the case.

I suspect that using direct IO to the PCI chipset is more likely to work in the
VSTa environment.

        J
Received on Fri Jun 26 17:18:45 1998