Building for ARM systems

[Aleix Pol]

On Fri, Mar 17, 2017 at 6:28 PM, Dan Nicholson <nicholson at endlessm.com> wrote:
> On Thu, Mar 16, 2017 at 8:56 PM, Aleix Pol <aleixpol at kde.org> wrote:
>>
>> I've been trying it for a bit more, I am getting these contents now,
>> still getting the same execvp error message.
>>
>> # cat /proc/sys/fs/binfmt_misc/qemu-arm
>> enabled
>> interpreter /usr/bin/qemu-arm-static
>> flags:
>> offset 0
>> magic 7f454c4601010100000000000000000002002800
>> mask ffffffffffffff00fffffffffffffffffeffffff
>
> Ah, I lied. I thought that the behavior of the kernel was to make the
> new "F" feature default if the flags were not set. Now I actually
> tried on yakkety and it fails. Here's my full working test recipe.
>
> # apt-get install qemu-user-static
> # update-binfmts --package qemu-user-static --remove qemu-arm
> /usr/bin/qemu-arm-static
> # echo ":qemu-arm:M::\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-arm-static:OFC"
>> /etc/binfmt.d/qemu-arm.conf
> # systemctl restart systemd-binfmt.service
> # cat /proc/sys/fs/binfmt_misc/qemu-arm
> enabled
> interpreter /usr/bin/qemu-arm-static
> flags: OCF
> offset 0
> magic 7f454c4601010100000000000000000002002800
> mask ffffffffffffff00fffffffffffffffffeffffff
>
> The OC aren't to my knowledge needed, but that just maintains the way
> that the qemu-user-static set it up with the additional F flag. Now
> for a test with a debootstraped armhf system. Note that if the above
> isn't working, I'd have to use qemu-debootstrap which copies
> /usr/bin/qemu-arm-static into the target system.
>
> # apt-get install debootstrap debian-archive-keyring
> # debootstrap --arch=armhf unstable unstable
> # chroot unstable ls
> bin   dev  home  media    opt   root  sbin  sys  usr
> boot  etc  lib     mnt    proc  run   srv   tmp  var
>
> Success! I haven't actually tested flatpak yet in this scenario, but
> I'm confident it will succeed.
>
> Looks like there's a debian bug for supporting the F flag in
> binfmt-support -
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=853820. After that
> the qemu-user-static package would need to be updated to make use of
> the new binfmt-support feature. Or, even better, binfmt-support adds F
> by default if the kernel supports it with maybe an option to disable
> it.

Oh, I see. Well, this makes me happy, now it's compiling things!
Terribly slow, but it is doing things. I'll leave it overnight and see
how far we can go.

Thank you a lot, Dan!
Aleix