From: Gert Wollny <gert.wollny@collabora.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: linux-kernel@vger.kernel.org, David Airlie <airlied@linux.ie>,
Tomeu Vizoso <tomeu.vizoso@collabora.com>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [PATCH v7] Add udmabuf misc device
Date: Mon, 10 Sep 2018 16:17:02 +0200 [thread overview]
Message-ID: <1536589022.4810.72.camel@collabora.com> (raw)
In-Reply-To: <20180910133050.tr2lozfmhimqs4c4@sirius.home.kraxel.org>
Am Montag, den 10.09.2018, 15:30 +0200 schrieb Gerd Hoffmann:
> On Mon, Sep 10, 2018 at 01:31:08PM +0200, Gert Wollny wrote:
> > Am Montag, den 10.09.2018, 12:53 +0200 schrieb Gerd Hoffmann:
> > >
> > > By default qemu doesn't use memfd for backing storage, you have
> > > to
> > > explicitly configure qemu that way (see qemu commit log of the
> > > test
> > > branch):
> > >
> > > qemu-system-x86_64 -m 2G
> > > -object memory-backend-memfd,id=ram,size=2G
> > > -numa node,memdev=ram"
> >
> > Thanks, but that doesn't seem to help.
>
> Note the memory is specified twice, once with -m, once for the
> memory-backend-memfd object. The two must match of course (or, to be
> exact, the sum of all memory backends must match the total memory,
> but unless you want create a virtual numa machine there is no reason
> to have multiple memory-backends).
Qemu actually complained when it was not the same.
>
> > Are there any host kernel configuration parameters or features that
> > I should set (apart from enabling udmabuf)?
>
> I'm not aware of any unusual parameters required. My config is based
> on rhel-7, then stripped down with localmodconfig, then enabled the
> bits I want in my test kernel.
I use Gentoo and my kernel is rather stripped down ...
>
> Oh, wait, CONFIG_MEMFD_CREATE could be the one. I guess I should add
> a Kconfig dependency.
This was enabled, so not sure what else could be missing, I guess I'll
have to add some logging to get an idea.
Best,
Gert
next prev parent reply other threads:[~2018-09-10 14:17 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-09 11:11 [PATCH v7] Add udmabuf misc device Gert Wollny
2018-09-10 8:37 ` Gerd Hoffmann
2018-09-10 9:18 ` Gert Wollny
2018-09-10 10:53 ` Gerd Hoffmann
2018-09-10 11:31 ` Gert Wollny
2018-09-10 13:30 ` Gerd Hoffmann
2018-09-10 14:17 ` Gert Wollny [this message]
2018-09-10 16:26 ` Gert Wollny
2018-09-10 17:39 ` Gert Wollny
-- strict thread matches above, loose matches on Subject: below --
2018-08-27 9:34 Gerd Hoffmann
2018-08-31 8:48 ` Daniel Vetter
2018-09-10 12:12 ` Laurent Pinchart
2018-09-11 6:50 ` Gerd Hoffmann
2018-09-11 9:50 ` Laurent Pinchart
2018-09-11 10:05 ` Daniel Vetter
2018-09-11 12:03 ` Gerd Hoffmann
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