[ofw] RE: Possible IPoIB DMA problems

[Anh Duong]

There are X86-64 based servers with IOMMUs out there such as IBM
high-end System x Servers.  As such CPU and Bus addresses are different
on these systems.

> -----Original Message-----
> From: Alex Estrin
> Sent: Thursday, August 21, 2008 1:03 PM
> To: Fab Tillier; Anh Duong; ofw at lists.openfabrics.org
> Cc: Stan C. Smith; John Russo; Tzachi Dar; Usha Srinivasan
> Subject: RE: Possible IPoIB DMA problems
> 
> 
> 
> > -----Original Message-----
> > From: Fab Tillier [mailto:ftillier at windows.microsoft.com]
> > Sent: Thursday, August 21, 2008 12:44 PM
> > To: Alex Estrin; Anh Duong; ofw at lists.openfabrics.org
> > Cc: Stan C. Smith; John Russo; Tzachi Dar; Usha Srinivasan
> > Subject: RE: Possible IPoIB DMA problems
> >
> >
> >
> > >From: Alex Estrin [mailto:alex.estrin at qlogic.com]
> > >Sent: Thursday, August 21, 2008 9:28 AM
> > >
> > >From your examples ... these are the places where
> > appropriate physical
> > >address is taken from virtual.
> > >preparing send WR.
> >
> > The physical address returned is CPU-relative, not bus
> > relative.  These can be different, but generally have not
> > been on x86/x64 platforms.
> 
> It should be fine as long as CPU and bus mapped to the same address
space.
> 
> > -Fab
> >