UIO Devices and user processes

[Yann Droneaud]

Le mardi 06 octobre 2015 à 09:26 -0400, Kenneth Adam Miller a écrit :

> Any body know about the issue of assigning a process a region of
> physical memory to use for it's malloc and free? I'd like to just
> have the process call through to a UIO driver with an ioctl, and then
> once that's done it gets all it's memory from a specific region.
> 

You mean CONFIG_UIO_DMEM_GENIRQ (drivers/uio/uio_dmem_genirq.c)

See:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=0a0c3b5a24bd802b1ebbf99e0b01296647b8199b
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b533a83008c3fb4983c1213276790cacd39b518f
https://www.kernel.org/doc/htmldocs/uio-howto/using-uio_dmem_genirq.html


PS: please don't top post reply as it makes it difficult to parse the
discussion.


> On Tue, Oct 6, 2015 at 1:21 AM, Greg KH <greg at kroah.com> wrote:
> > On Mon, Oct 05, 2015 at 07:07:51PM -0400, Kenneth Adam Miller
> > wrote:
> > > So, I'm reading about UIO devices and user processes for mapping
> > memory into
> > > userland, and basically I have just a couple questions:
> > >
> > > What happens when a userland processes has allocated some
> > resource from a
> > > driver that is facilitating UIO, but then subsequently crashes?
> > I'd like to
> > > know that the driver can (or how you would enable such) recover
> > the resources
> > > so that the next user process can acquire them, instead of them
> > being lost.
> > 
> > Have you tried this?  All of your resources should be freed
> > properly, if
> > not, let the uio maintainers know.
> > 
> > thanks,
> > 

Regards.

-- 
Yann Droneaud
OPTEYA