Re: [Qemu-devel] failed kpartx on qemu-aarch64-static

[Chanho Park]

Hi Peter,

On Tuesday, July 5, 2016, Peter Maydell <address@hidden> wrote:

> On 2 July 2016 at 19:23, Peter Maydell <address@hidden
> <javascript:;>> wrote:
> > On 2 July 2016 at 17:25, Chanho Park <address@hidden <javascript:;>>
> wrote:
> >> I've got a kpartx crash frin qemu-aarch64 user emulation.
> >> The version of qemu-aarch64-static is 2.5.0 and it was also occurred
> >> on 2.5.1 version.
> >>
> >> /usr/bin/qemu-aarch64-static --version
> >> qemu-aarch64 version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.1), Copyright
> >> (c) 2003-2008 Fabrice Bellard
> >>
> >> == Bug report ==
> >> kpartx -a -v test.img
> >> Unsupported ioctl: cmd=0x4c82
> >
> > That's QEMU saying we don't support the ioctl, which is
> > LOOP_CTL_GET_FREE.
> >
> >> *** stack smashing detected ***: /usr/sbin/kpartx terminated
> >> ======= Backtrace: =========
> >> /lib64/libc.so.6(+0x6e334)[0x400091d334]
> >> /lib64/libc.so.6(__fortify_fail+0x48)[0x400099dd60]
> >> /lib64/libc.so.6(+0xeed14)[0x400099dd14]
> >> /usr/sbin/kpartx[0x40385c]
> >> /usr/sbin/kpartx(read_gpt_pt+0x40)[0x404710]
> >> /usr/sbin/kpartx[0x402794]
> >> /lib64/libc.so.6(__libc_start_main+0xe8)[0x40008ce810]
> >> /usr/sbin/kpartx[0x403100]
> >
> > This might be the result of kpartx's error handling
> > code not reacting well to the ioctl failing, or it might
> > be a different problem.
>
> I got round to testing this with current master myself.
> It turns out to be a bug in our handling of the BSGSSZGET
> ioctl; we were using the wrong type for it which meant
> we would write to more memory than we should have if the
> guest was a 64-bit one. I'll send a patch in a moment.
>

Thanks. I've checked your patch has been fixed the problem.

Anyway, there is one more problem.
When I tries to detach the loop device using "kpartx -d" command, it was
not detached correctly. Below is my test sequence.

dd if=/dev/zero of=test.img bs=1M count=32
fdisk test.img << __EOF__
n
p



w
__EOF__

kpartx -a -v test4.img
Unsupported ioctl: cmd=0x4c82
add map loop3p1 (252:2) 0 63488 linear /dev/loop3 2048

kpartx -d test4.img
<- I expected the loop3 and loop3p1 are detached, but they weren't.

Best regards,
Chanho Park


-- 
Best Regards,
Chanho Park