Re: [Qemu-devel] VirtIO 9p mount_tag (bogus?) limit of 32 bytes

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

On Tue, 21 Feb 2012 21:58:39 -0600, C Anthony Risinger <anthony@xtfx.me> wrote:
> On Sat, Feb 18, 2012 at 11:38 AM, Aneesh Kumar K.V
> <aneesh.kumar@linux.vnet.ibm.com> wrote:
> > On Thu, 16 Feb 2012 06:20:21 -0600, C Anthony Risinger <anthony@xtfx.me> wrote:
> >> a) mapped FS security policy (xattrs) causes `ldconfig` to abort()?
> >> root or normal user ...
> >>
> >> somehow `ldconfig` gets a duplicate inode while constructing the
> >> cache, even though it already de-duped (confirmed via gdb and grep --
> >> only a single abort() in the source)
> >>

I will try to reproduce this to get more info.


> >> b) unable to run `locale-gen` on *any* virtfs configuration? (strace)
> >>
> >> [...]
> >> mmap(NULL, 536870912, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
> >> 0x7fb3aac63000
> >> mmap(0x7fb3aac63000, 103860, PROT_READ|PROT_WRITE,
> >> MAP_SHARED|MAP_FIXED, 3, 0) = -1 EINVAL (Invalid argument)
> >> cannot map archive header: Invalid argument
> >>

For writable mmap to work you need to mount with -o cache=loose. Did
you try local-gen with that mount option ?


> >> c) package files containing device nodes fail (maybe this is expected
> >> ...); specifically `/lib/udev/devices/loop0`
> >>
> >

Does this mean mknod fails for you. Or is something else in package
manager causing the failure ? 


> > Is this with 9p2000.L ?. What is the guest kernel version ?
> 
> (not sure if list will accept this ... too much traffic! had to remove myself)
> 
> yes this is with 9p2000.L, both host and guests run kernel 3.2.5.  i'm
> happy to provide/try additional information/tests if useful.
> 

One quick thing you could do is to try latest linus kernel as the guest
kernel. 

> ... is there really no chance of upping the max path?  seems like
> config space will be a big constraint, forever :-(
> 
> and i'm very much willing to do additional testing for the other
> issues as well (i had to revert to qemu-as-root to get passthru
> working 100% on rootfs ... ldconfig is kind of critical :-).  are
> these known issues?
> 

I don't have much suggestion on what could be going wrong there. I will
try to reproduce the ldconfig issue here.

-aneesh