Re: [Qemu-devel] [PULL 00/24] Linux-user updates

[Joakim Tjernlund]

Riku Voipio <address@hidden> wrote on 2014/08/18 15:17:06:
> 
> On 18 August 2014 15:59, Joakim Tjernlund 
<address@hidden> wrote:
> > Peter Maydell <address@hidden> wrote on 2014/08/18 14:45:49:
> >> I'm sure there are cases which don't work; but we should try
> >> to find a way which allows us to make those work (with a
> >> recommended change to binfmt misc registration) which
> >> doesn't break the old configs in the process.
> 
> > This was considered/discussed to some point and no-one could come up
> > with a better approach.
> 
> A lot of people are OK with the current approach. Really few
> applications become unhappy if say,called "/bin/ls" instead of "ls".
> So saying things are "broken" without switching to P flag is a bit
> myopic view. In my experience, only some testsuites suffer failures.

semibroken but OK, that was a bit much too. 

> 
> The problem with updating the binfmt registration is that people may
> have a mix of old and new qemu binaries. When we change the
> registration, it means no old qemu anymore works. The "argc > 3" is
> also a bit weak - it means that calling "ls -la ." would pass the test
> even if "P" flag is not set, but qemu would pass wrong parameters to
> the binary being run.

Yes, it does not catch all error cases but I figured it was better than no
error check at all.

> 
> No doubt starting to use the P flag would be a improvement. But it
> would be good to find a less breaky way manage the transition.

Yes it would but none of us came up with a better way at the time and you 
were OK
with my patch in the end. Now I don't have time to dwell on this, sorry.

 Jocke

PS.
   Crazy idea, you could read /proc/sys/fs/binfmt_misc/$ARCH and parse the 
flags
   field if you can live with the performance hit.