Messages in this thread | | | Date | Fri, 15 Jul 2016 20:42:54 +0900 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH RFC] uio: allow use on nommu systems |
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On Thu, Jul 14, 2016 at 09:58:29PM -0400, Rich Felker wrote: > On Fri, Jul 15, 2016 at 10:42:37AM +0900, Greg Kroah-Hartman wrote: > > On Thu, Jul 14, 2016 at 08:53:06PM -0400, Rich Felker wrote: > > > mmap of uio devices does not seem to work without further > > > nommu-specific support, but interrupt handling already works, and > > > userspace drivers for nommu systems can simply use physical mmio > > > addresses from userspace directly anyway without mmap. > > > > > > Signed-off-by: Rich Felker <dalias@libc.org> > > > --- > > > > > > I don't particularly expect this to be accepted upstream as-is, but > > > since we're actually trying to use the UIO subsystem on nommu (J2), > > > I'd like to start a discussion of what an acceptable patch would > > > entail. > > > > > > The uio_pdrv_genirq driver was tested on J2 with this patch and > > > interrupt handling works as expected. > > > > > > drivers/uio/Kconfig | 1 - > > > 1 file changed, 1 deletion(-) > > > > > > diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig > > > index 52c98ce..387b2bb 100644 > > > --- a/drivers/uio/Kconfig > > > +++ b/drivers/uio/Kconfig > > > @@ -1,6 +1,5 @@ > > > menuconfig UIO > > > tristate "Userspace I/O drivers" > > > - depends on MMU > > > > This doesn't seem to do much, don't you need to modify uio-specific > > drivers? Or given that the core uio code doesn't rely on mmu, is this > > safe? > > As noted above, mmap of the device does not work (returns error); I > don't understand why.
Try working that out and then we can talk :)
thanks,
greg k-h
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