While running in debug mode if 9P server is unable to open the log file
it results in a SEGV deep down in glibc:
Program received signal SIGSEGV, Segmentation fault.
0x008fca8c in fwrite () from /lib/libc.so.6
(gdb) bt
#0 0x008fca8c in fwrite () from /lib/libc.so.6
#1 0x081eb87e in pprint_pdu (pdu=0x89a52e1c)
at /data/sripathi/code/qemu/new/qemu-next-upstream/hw/virtio-9p-debug.c:380
#2 0x0806dad8 in submit_pdu (s=0x897dc008, pdu=0x89a52e1c)
at /data/sripathi/code/qemu/new/qemu-next-upstream/hw/virtio-9p.c:3092
#3 0x0806dc63 in handle_9p_output (vdev=0x897dc008, vq=0x86d8218)
at /data/sripathi/code/qemu/new/qemu-next-upstream/hw/virtio-9p.c:3122
#4 0x081ac728 in virtio_queue_notify (vdev=0x897dc008, n=0)
at /data/sripathi/code/qemu/new/qemu-next-upstream/hw/virtio.c:563
#5 0x08063876 in virtio_ioport_write (opaque=0x86d7b98, addr=16, val=0)
at /data/sripathi/code/qemu/new/qemu-next-upstream/hw/virtio-pci.c:222
#6 0x08063e26 in virtio_pci_config_writew (opaque=0x86d7b98, addr=16, val=0)
at /data/sripathi/code/qemu/new/qemu-next-upstream/hw/virtio-pci.c:357
#7 0x080c881a in ioport_write (index=1, address=49296, data=0) at ioport.c:80
#8 0x080c8d4c in cpu_outw (addr=49296, val=0) at ioport.c:204
#9 0x08073010 in kvm_handle_io (port=49296, data=0xab393000, direction=1, size=2, count=1)
at /data/sripathi/code/qemu/new/qemu-next-upstream/kvm-all.c:735
...
...
This is ugly and misleading. The following patch adds a BUG_ON to catch this
error. With this patch we get an abort message like the following, which makes
it easier to analyze:
f12-kvm login: qemu: /data/sripathi/code/qemu/new/qemu-next-upstream/hw/virtio-9p-debug.c:353: pprint_pdu: Assertion `!(!llogfile)' failed.
Signed-off-by: Sripathi Kodi <sripathik@in.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This patch fluesh the debug messages to the log file at the end of each
debug message.
Changes from V1:
Used fflush instead fseek for the flush.
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This patch doesn't implement the 9p protocol handling
code. It adds a simple device which dump the protocol data.
[jvrao@linux.vnet.ibm.com: Little-Endian to host format conversion]
[aneesh.kumar@linux.vnet.ibm.com: Multiple-mounts support]
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
