Re: [Qemu-discuss] Another qemu chroot unsupported syscall question

[Peter Maydell]

On 19 September 2014 05:11, Dave Flogeras <address@hidden> wrote:
> Similar to yesterday, in my qemu chroot
> (armv6j-hardfloat-linux-musleabi) I am seeing un-supported syscalls
> related to get/set/list xattr.  However, unlike yesterday, I looked
> into the linux-user/arm/syscall_nr.h and those syscalls (226 through
> 237) seem to be wrapped.
>
> The file system that I am running on does not in fact have extended
> attribute support.  However the difference I am seeing is that on the
> host system "getfattr ." returns nothing with a return code 0, while
> inside of the chroot I see:
>
> qemu: Unsupported syscall: 235
> setfattr: /root/a.out: Function not implemented
>
> and it returns 1.
>
> I also notice while configuring/compiling software inside of the
> chroot I get a multitude of other unsupported syscalls in the
> NR_***attr family of functions.
>
> What am I misunderstanding?

QEMU probes for whether the host system supports the *attr
library calls at configure time; if they don't exist it falls
back to providing a QEMU which doesn't implement these syscalls.
You need to install a recent glibc or (on older distros)
libattr. If you pass configure '--enable-attr' it will fail
noisily if the probe fails rather than quietly falling back
to not supporting the syscalls.

thanks
-- PMM