Jonas Meurer
2013-May-15 08:00 UTC
[Pkg-xen-devel] Bug#708344: xen: serial passthrough broken in Debian Wheezy
Package: src:linux Version: 3.2.41-2 Severity: important Hello, I just discovered a strange bug with serial passthrough in xen 4.1 on Debian Wheezy. The Dom0 has a GSM modem connected to serial port. The serial port is passed through to a DomU with options 'irq = [ 4 ]' and 'ioports = [ '3f8-3ff ]'. This worked as expected on Debian Squeeze with Xen 4.0 and Linux kernel 2.6.32 (both for Dom0 and DomU). On Debian Wheezy with Xen 4.1 and Linux kernel 3.2.0 the passthrough seems to work as well (/dev/ttyS0 appears in dmesg of DomU), but something is wrong. The GSM modem doesn't behave as expected. The smstools daemon errors out with 'Cannot open serial port /dev/ttyS0, error: Function not implemented'. It took me hours to find the difference, but it seems like the guest (domU) kernel is the problem. The setup keeps working when Dom0 is upgraded to Debian Wheezy with Xen 4.1 and linux kernel 3.2.0. It even keeps working if the DomU userland is upgraded to Debian Wheezy. Only if I upgrade the DomU linux kernel to 3.2.0 from Wheezy as well, smstools stops working. I don't expect this to be a smstools bug. More likely, something regarding serial pass through functions of xen is broken in 3.2.0 kernel from Debian Wheezy. Please give me advice on how to provide additional information. Kind regards, jonas -- Package-specific info: ** Version: Linux version 3.2.0-4-amd64 (debian-kernel at lists.debian.org) (gcc version 4.6.3 (Debian 4.6.3-14) ) #1 SMP Debian 3.2.35-2 -- System Information: Debian Release: 7.0 APT prefers stable APT policy: (500, 'stable') Architecture: amd64 (x86_64) Kernel: Linux 3.2.0-4-amd64 (SMP w/1 CPU core) Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968) Shell: /bin/sh linked to /bin/dash