Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]


Groups > linux.kernel > #1198928

Re: [PATCH 2/2] iommu/vt-d: Report superpage support in sysfs

From Alex Williamson <alex.williamson@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH 2/2] iommu/vt-d: Report superpage support in sysfs
Date 2015-08-03 17:10 +0200
Message-ID <pTpxg-6Ex-23@gated-at.bofh.it> (permalink)
References <pMfW1-3UL-3@gated-at.bofh.it> <pMfW1-3UL-1@gated-at.bofh.it> <pTp4e-5QN-35@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw


On Mon, 2015-08-03 at 16:30 +0200, Joerg Roedel wrote:
> On Tue, Jul 14, 2015 at 03:25:04PM -0600, Alex Williamson wrote:
> > We already have the VT-d capability register printed raw, but it
> > typically involves a trip to the code or the spec to figure out
> > whether superpages are supported.  Make this easier with "2M_pages"
> > and "1G_pages" sysfs entries that clearly report Y/N.
> > 
> > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> > ---
> >  drivers/iommu/intel-iommu.c |   22 ++++++++++++++++++++++
> >  1 file changed, 22 insertions(+)
> 
> Can we make this a generic entry for all iommu types and export a
> pagesize bitmap instead?

Are you suggesting a bitmap in order to have a consistent interface,
independently implemented by each IOMMU driver, or are you suggesting a
common interface implemented by iommu_ops.pgsize_bitmap?  The latter is
pretty well broken already.  It can't represent different IOMMU hardware
units having different capabilities, and it's broken by drivers like
intel-iommu that don't expose native hardware page sizes, but anything
that can be broken down into native hardware page size, so ~(4k-1).

Programatically, a bitmap is a concise way to expose multiple page
sizes, but for human consumption, it's not an ideal solution.  Thanks,

Alex

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | NextPrevious in thread | Find similar | Unroll thread


Thread

Re: [PATCH 2/2] iommu/vt-d: Report superpage support in sysfs Joerg Roedel <joro@8bytes.org> - 2015-08-03 16:40 +0200
  Re: [PATCH 2/2] iommu/vt-d: Report superpage support in sysfs David Woodhouse <dwmw2@infradead.org> - 2015-08-03 16:40 +0200
  Re: [PATCH 2/2] iommu/vt-d: Report superpage support in sysfs Alex Williamson <alex.williamson@redhat.com> - 2015-08-03 17:10 +0200

csiph-web