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RE: [Xen-devel] Re: [PATCH] infiniband/mthca : Fix userland mapping of m

To: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, Roland Dreier <rdreier@xxxxxxxxx>, Tziporet Koren <tziporet@xxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Re: [PATCH] infiniband/mthca : Fix userland mapping of mthca infiniband cards in Xen dom0
From: Jack Morgenstein <jackm@xxxxxxxxxxxxxx>
Date: Sun, 9 Jan 2011 10:24:02 +0200
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Thread-topic: [Xen-devel] Re: [PATCH] infiniband/mthca : Fix userland mapping of mthca infiniband cards in Xen dom0
We have no plans at present to test mthca on Xen. Our current Xen testing is 
focused on Connectx.


-----Original Message-----
From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@xxxxxxxxxx]
Sent: Friday, January 07, 2011 9:16 PM
To: Roland Dreier
Cc: Vivien Bernet-Rollande; Jack Morgenstein; Jeremy Fitzhardinge; 
xen-devel@xxxxxxxxxxxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx; rdreir@xxxxxxxxx; 
Subject: Re: [Xen-devel] Re: [PATCH] infiniband/mthca : Fix userland mapping of 
mthca infiniband cards in Xen dom0

On Thu, Jan 06, 2011 at 10:51:57AM -0800, Roland Dreier wrote:
>  > There is another way, which I hope can fix this issue (it fixes
>  > the graphics drivers). Basically making the Xen MMU be aware of the E820
>  > and consider any access to PFNs that are not in RAM to have VM_IO 
> implicitly set.
>  >
>  > The patches are at 
> git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git
>  >
>  > stable/p2m-identity.v4.3
>  >
>  > And posted on LKML )https://lkml.org/lkml/2010/12/30/163)
>  >
>  > They _should_ take care of your problem as long as the PFNs you
>  > are mapping fall within the PCI BAR regions (which I would presume they
>  > do since you are using ioremap).
> Yes, that should work fine for all the cases I know of in the RDMA
> drivers.  We are just mapping some PCI BAR space into userspace for
> direct access to hardware (just like graphics, I think).

Allright, then it will work.

I've respun another version that fundamentally does the same thing
but accounts for  "what PFN is non-RAM" in a much cleaner way.

It is @:


will post it soon on LKML.

Jack, Vivien: i you do merge it in your tree for testing with Xen and it works 
properly can
I attach your 'Tested-by' on the patch-set?

> I definitely prefer a solution that doesn't require driver authors to
> add a Xen-specific fix that isn't required on any other architecture.

Heh. You and me are on the same wavelength here.

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