On Thu, Apr 29, 2010 at 12:29:40PM -0700, Tom Lyon wrote:
> Michael, et al - sorry for the delay, but I've been digesting the comments 
> and researching new approaches.
> 
> I think the plan for V4 will be to take things entirely out of the UIO 
> framework, and instead have a driver which supports user mode use of 
> "well-behaved" PCI devices. I would like to use read and write to support 
> access to memory regions, IO regions,  or PCI config space. Config space is a 
> bitch because not everything is safe to read or write, but I've come up with 
> a table driven approach which can be run-time extended for non-compliant 
> devices (under root control) which could then enable non-privileged users. 
> For instance, OHCI 1394 devices use a dword in config space which is not 
> formatted as a PCI capability, root can use sysfs to enable access:
>       echo <offset> <readbits> <writebits> > 
> /sys/dev/pci/devices/xxxx:xx:xx.x/<yyy>/config_permit
> 
> 
> A "well-behaved" PCI device must have memory BARs >= 4K for mmaping, must 
> have separate memory space for MSI-X that does not need mmaping
> by the user driver, must support the PCI 2.3 interrupt masking, and must not 
> go totally crazy with PCI config space (tg3 is real ugly, e1000 is fine).

How about page aligned BARs?
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