Building for ARM systems

[Dan Nicholson]

On Mar 13, 2017 9:19 PM, "Aleix Pol" <aleixpol at kde.org> wrote:

On Mon, Mar 13, 2017 at 4:55 PM, Dan Nicholson <nicholson at endlessm.com>
wrote:
> On Mon, Mar 13, 2017 at 10:08 AM, Aleix Pol <aleixpol at kde.org> wrote:
>> On Tue, Mar 7, 2017 at 1:08 PM, Dan Nicholson <nicholson at endlessm.com>
wrote:
>>> On Tue, Mar 7, 2017 at 4:58 AM, Bastien Nocera <hadess at hadess.net>
wrote:
>>>> On Tue, 2017-03-07 at 03:05 +0100, Aleix Pol wrote:
>>>>> Dear Flatpak'ers,
>>>>> As some of you already know, I've been poking around trying to find
>>>>> some kind of system where we can build the KDE runtime and
>>>>> applications for ARM.
>>>>
>>>> For the applications, the fix is a package install on the build system,
>>>> and a flatpak-builder option away. See this post as well as the
>>>> original one:
>>>> http://www.hadess.net/2016/10/flatpak-cross-compilation-support.html
>>>
>>> We use this QEMU setup at Endless for our ARM apps. It's slow but
>>> works fine for apps. I think building a whole runtime would be
>>> painful, but you could give it a shot.
>>>
>>> The details in Bastien's post is that if you have qemu-user-static
>>> installed with the appropriate binfmts (usually provided in distro
>>> packaging), then you can run binaries emulated for any architecture
>>> QEMU supports. On linux-4.8+, the interpreter associated with the
>>> binfmt is opened immediately by the kernel and kept open so it doesn't
>>> need to live in the mount namespace setup by flatpak. Pass the
>>> appropriate arch to flatpak-builder and it magically works.
>>>
>>> On older kernels you can still do it, but you have to somehow get the
>>> interpreter path used in the binfmt definition included in the
>>> sandbox. One way would be to include qemu-user-static in the SDK at
>>> the same path as the host (e.g., /usr/bin/qemu-arm-static). What I did
>>> at Endless was hack the binfmt definition to use /run/qemu-arm-static
>>> and then add a bind mount from the host into the sandbox at that
>>> location.
>>
>> Hi,
>> So since nothing was really working and the cosmos doesn't seem to be
>> keen on offering proper ARM systems, I decided to give it a go.
>>
>> Yet, I'm getting an error message at the first thing ever executed:
>> execvp ./configure: No such file or directory
>>
>> Any idea what can be wrong?
>>
>> Aleix
>>
>> PS: I'm testing this on ubuntu yakkety (kernel 4.8.0) and the flatpak ppa
>
> That indicates that you don't have the binfmt support enabled because
> that essentially means that it can't run the ARM /bin/sh (I'm pretty
> sure). Do you have /proc/sys/fs/binfmt_misc/qemu-arm? Does
> /proc/sys/fs/binfmt_misc/status say "enabled"? Can you do something
> simple like "flatpak build $build_dir bash"?

Sounds like something is wrong in my system?
Maybe a permissions issue?

Aleix

$ flatpak build sdk bash
execvp bash: No such file or directory
$ cat /proc/sys/fs/binfmt_misc/status
enabled
$ ls -l /proc/sys/fs/binfmt_misc/qemu-arm
-rw-r--r-- 1 root root 0 mar 13 14:19 /proc/sys/fs/binfmt_misc/qemu-arm


Can you show the contents of that qemu-arm file?
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