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FS#36992 - [linux] 3.11.x causes shared folder problems (9p) when used as kvm guest

Attached to Project: Arch Linux
Opened by Manuel Reimer (M-Reimer) - Thursday, 19 September 2013, 18:24 GMT
Last edited by Tobias Powalowski (tpowa) - Thursday, 10 October 2013, 10:05 GMT
Task Type Bug Report
Category Upstream Bugs
Status Closed
Assigned To Tobias Powalowski (tpowa)
Thomas Bächler (brain0)
Architecture All
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No


In my archlinux system, running as kvm guest on an archlinux host, I have problems with shared folders (using the "9p" file system), since I upgraded the kernel in my guest system to 3.11.1.

All shared folders are now in "read only" mode. Guests are no longer able to write.

I was able to fix this by switching "security_model", in the "-virtfs" parameter to qemu, from "passthrough" to "mapped", but then any try to execute a script from the mounted shared folder results in:

-bash: ./ /usr/bin/perl: bad interpreter: Numerical result out of range

I've downgraded the guest system to linux 3.10.9 and this immediately fixed this issue.

After doing so, I was able to switch back the security model to "passthrough". Writing works. Executing scripts from the mounted shared folder works, too.

For me it seems like "9p" is broken on Linux 3.11.1.

The host system is not affected. There, I can keep with 3.11.1 without causing any kvm problems.

Can someone please find out if there is a patch available for this and perhaps ship an updated kernel package?
This task depends upon

Closed by  Tobias Powalowski (tpowa)
Thursday, 10 October 2013, 10:05 GMT
Reason for closing:  Upstream
Comment by Gerardo Exequiel Pozzi (djgera) - Thursday, 26 September 2013, 01:10 GMT
Please report to upstream. There is nothing to do here. Thanks.