From: Chas Williams <3chas3@gmail.com>
To: Thomas Monjalon <thomas@monjalon.net>
Cc: Chas Williams <chas3@att.com>, dev@dpdk.org, anatoly.burakov@intel.com
Subject: Re: [dpdk-dev] [PATCH] eal: add option to force IOVA as PA mode
Date: Thu, 11 Jan 2018 22:28:59 -0500 [thread overview]
Message-ID: <CAG2-Gk=u4yau2CEMs+02wGZc3Pv=JKd9+11u9Tpres3UDw-1Og@mail.gmail.com> (raw)
In-Reply-To: <1773541.G656isd0hF@xps>
Thanks, and yes I already saw that. That seems like a much better
solution. I will give it a spin in my box with this problem.
On Thu, Jan 11, 2018 at 7:12 PM, Thomas Monjalon <thomas@monjalon.net>
wrote:
> 03/12/2017 01:23, Chas Williams:
> > The particular machine in my case is a Dell Optiplex 790 which is fairly
> > similar to another system that has basically the same problem. The IOMMU
> > advertises that is can only handle 39 bits of addressing. The DMAR
> address
> > tables have a width of 36 bits, so all is well when using IOVA physical
> > addresses. With IOVA virtual addresses, they sometimes go beyond the 39
> > bit boundary. I was under the impression that IOMMU widths are more
> > typically 48 bits, but I appear to have some low end systems with a
> simpler
> > IOMMU.
> >
> > I could make it a runtime option.
> >
> > On Thu, Nov 30, 2017 at 4:17 AM, Thomas Monjalon <thomas@monjalon.net>
> > wrote:
> >
> > > 30/11/2017 03:57, Chas Williams:
> > > > From: Chas Williams <chas3@att.com>
> > > >
> > > > The IOMMU in some machines report that they can only support
> > > > limited widths. IOVA virtual addresses may exceed this width
> > > > making the use of IOVA virtual addresses difficult. The option
> > > > CONFIG_RTE_LIBRTE_USE_PHYS_IOVA can used to force IOVA physical
> > > > address usage.
> > >
> > > Which machines are you talking about?
> > > A run-time option may be a better solution.
>
> Please check the patch from Maxime:
> https://dpdk.org/dev/patchwork/patch/33192/
>
>
>
next prev parent reply other threads:[~2018-01-12 3:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-30 2:57 Chas Williams
2017-11-30 9:17 ` Thomas Monjalon
2017-12-03 0:23 ` Chas Williams
2018-01-12 0:12 ` Thomas Monjalon
2018-01-12 3:28 ` Chas Williams [this message]
2017-12-01 5:48 ` Hemant Agrawal
2017-12-03 0:25 ` Chas Williams
-- strict thread matches above, loose matches on Subject: below --
2017-11-30 2:57 Chas Williams
2017-11-30 2:56 Chas Williams
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