Re: [PATCH v2 10/11] gpiolib: add new ioctl() for monitoring changes in line info
From: Andy Shevchenko
Date: Tue Dec 10 2019 - 12:00:21 EST
On Fri, Dec 6, 2019 at 11:20 PM Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
> czw., 5 gru 2019 o 18:02 Andy Shevchenko <andy.shevchenko@xxxxxxxxx> napisaÅ(a):
> > On Thu, Dec 5, 2019 at 3:47 PM Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
> > > czw., 5 gru 2019 o 11:27 Andy Shevchenko <andy.shevchenko@xxxxxxxxx> napisaÅ(a):
> > > > On Thu, Dec 5, 2019 at 11:42 AM Bartosz Golaszewski
> > > > <bgolaszewski@xxxxxxxxxxxx> wrote:
> > > > > År., 4 gru 2019 o 23:34 Andy Shevchenko <andy.shevchenko@xxxxxxxxx> napisaÅ(a):
> > > > > > On Wed, Dec 4, 2019 at 6:03 PM Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
> > > > So, the test cases, I can imagine of, should include (k - kernel, u - user):
> > > > - 64k-64u: LE and BE
> > > > - 64k-32u: LE and BE
> > > > - 32k-32u: LE and BE
> > >
> > > I usually use qemu VMs built with yocto for testing but I don't see
> > > any way of creating a 32-bit user-space with 64-bit kernel. Any ideas
> > > on how to prepare a testing environment?
> > In my case it's very easy. I do
> > - compile kernel as 64-bit separately;
> > - compile initramfs of Buildroot distro with external kernel build provided.
> Any specific config options are needed on x86-64 kernel to use 32-bit
> user-space? I'm not well versed in x86 architectures, that's why I'm
> asking. I built a 32-bit userspace qemu image with yocto and then
> manually built a 64-bit kernel. I tried running it but I'm getting a
> kernel panic when the rootfs is being mounted.
Just published set of scripts  we are using internally for our development.
Find README.coreteam in the source root and read how to use that.
> On a different note: why would endianness be an issue here? 32-bit
> variables with 64-bit alignment should still be in the same place in
> memory, right?
With explicit padding, yes.
> Any reason not to use __packed for this structure and not deal with
> this whole compat mess?
Have been suggested that explicit padding is better approach.
(See my answer to Kent)
> I also noticed that my change will only allow user-space to read one
> event at a time which seems to be a regression with regard to the
> current implementation. I probably need to address this too.
Yes, but we have to have ABI v2 in place.
With Best Regards,