Re: [Xen-devel] [HYBRID]: XEN_EMULATE_PREFIX in user process

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2012-06-29 at 20:07 +0100, Mukesh Rathor wrote:
> On Fri, 29 Jun 2012 11:15:46 -0700
> Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> wrote:
> > > It's unlikely but not impossible for a userspace developer to have
> > > done some "Xen magic" and used the prefix in userspace.
> > > 
> > > What version of dm_mapper do you have? I checked the version in
> > > Debian Sid and it doesn't do this (at least not directly).
> > > 
> > > Are you able to run the dm_mapper process under gdb and inspect it
> > > to find the prefix?
> > 
> > Well, let me take that back. dm_mapper is the last printk, but it
> > could be anything after that or that. 
> > 
> > Unfortunately, it's dom0 and during boot, so can't run gdb on it. I am
> > hacking the kernel now to print every user process name in schedule.
> 
> Ah, it's "xen-detect" coming in right after dm_mapper. I see the
> xen prefix in it. Hmm... let me see if I can add some run time check
> for hybrid dom0, then won't have to worry about invalid_op trap. Less
> code that way. That's the end goal anyways...

I don't think reducing code should come at the expense of adding special
cases for hybrid to userspace programs...

I think you'll have to handle the invalid op, it can't be that much
code, can it?

Ian


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