From: Joakim Tjernlund <Joakim.Tjernlund@infinera.com>
To: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: uio_dmem_genirq.c and DMA mapping to user space ?
Date: Tue, 12 Sep 2017 14:08:27 +0000 [thread overview]
Message-ID: <1505225305.31322.113.camel@infinera.com> (raw)
In-Reply-To: <20170912123716.GA19626@kroah.com>
On Tue, 2017-09-12 at 05:37 -0700, gregkh@linuxfoundation.org wrote:
> On Tue, Sep 12, 2017 at 12:18:27PM +0000, Joakim Tjernlund wrote:
> > Hi
> >
> > I am trying to use the uio_dmem_genirq.c driver for allocating DMA memory to a PCI device
> > using the uio_pci_generic.c driver.
> >
> > I got as far as defining an UIO dev containing only Dynamic DMA memory and
> > now I am stuck.
> > I can see how DMA memory is allocated when opening the /dev/uio device but I cannot
> > figure out how to mmap this memory to User space as well so I can share this
> > memory with the PCI device and my user space driver.
> >
> > What am I missing?
>
> Why can't you call mmap() on the fd you created when you opened
> /dev/uio? What happens when you do that?
Haven't tried that as I figured it had to be something similar as UIO PCI
where you can have several memory regions and therefore must mmap one of
the resource files under sys:
# > pwd
/sys/bus/pci/drivers/uio_pci_generic/0000:01:00.0/uio/uio8/device
leipzig device # cat /sys/devices/platform/ffe250000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0/resource
0x0000000c10000000 0x0000000c11ffffff 0x0000000000140204
0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 0x0000000000000000
leipzig device # pwd
/sys/bus/pci/drivers/uio_pci_generic/0000:01:00.0/uio/uio8/device
leipzig device # cat resource
0x0000000c10000000 0x0000000c11ffffff 0x0000000000140204
0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 0x0000000000000000
leipzig device # ls resource*
resource resource0
Here one opens and mmaps resource0 to get at
0x0000000c10000000 0x0000000c11ffffff 0x0000000000140204
Jocke
prev parent reply other threads:[~2017-09-12 14:08 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-12 12:18 Joakim Tjernlund
2017-09-12 12:37 ` gregkh
2017-09-12 14:08 ` Joakim Tjernlund [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1505225305.31322.113.camel@infinera.com \
--to=joakim.tjernlund@infinera.com \
--cc=gregkh@linuxfoundation.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®