UIVM graphics
We managed to get the UIVM up and running. We can sshv4v to it using 1.0.0.x. The UIVM has xenfb2 loaded but it does not create a /dev/fb0 node. The problem is the backed is not created but surfman. The dmbus RPC to create the node and hook up the front back connection is never called:
surfman/src/rpc.c:rpc_connect(type=DEVICE_TYPE_XENFB)
It looks like the call should come from the dm-agent running in dom0 (not sure what that is even doing there).
Blktap dev passing to QEMU
We have deliberately disabled QEMU support for directly supplying a VHD as a drive. The proper way in OpenXT is by using a blktap device (such as tapdisk2). Even though one can signal to LibXL to use a tap device in the config file, LibXL will always pass a vhd as an argument to QEMU.
Consider the configuration:
disk = [ "tap2:tapdisk:vhd:/storage/disks/debian-7.8-x64-clean.vhd,xvda,rw" ]
Unfortunately, XL will pass the following to QEMU:
libxl: debug: libxl_dm.c:1237:libxl__spawn_local_dm: -drive
libxl: debug: libxl_dm.c:1237:libxl__spawn_local_dm: file=/storage/disks/debian-7.8-x64-clean.vhd,if=ide,index=0,media=disk,format=vpc,cache=writeback
This will likely need to be patched against XL.
VIF naming in hotplug scripts
When supplied a VIF in the config file via:
vif = [ "bridge=xenbr0,script=vif-bridge" ]
The supplied hotplug script (vif-bridge in /etc/xen/scripts/) is being called with vif$VIF_ID-emu instead of vif$VIF_ID where $VIF_ID starts at zero and increments every time and instance requests a VIF. Currently, the "-emu" part is being removed by sed. It is not 100% clear why the -emu is being appended.
HVMLOADER not loading ROMS...no video
The ROM loading was being skipped due to a missing xenstore value.
let local_stuff = [
"serial/0/limit", string_of_int 65536;
"console/limit", string_of_int 65536;
"console/port", string_of_int console_port;
"console/ring-ref", sprintf "%nu" console_mfn;
"hvmloader/bios", "seabios";
"hvmloader/seabios-legacy-load-roms", "1"; <--- that guy
] in
GDB and QEMU
Running QEMU in GDB has proven to be very helpful. Simply copy the gdb binaries (gdb, gdbserver, and gdbtui) on to your OpenXT machine and replace the /usr/lib/xen/bin/qemu-system-i386 script with:
#!/bin/bash
DOMID=`cat /tmp/domid`
let "NEWID=$DOMID+1"
echo "$NEWID" > /tmp/domid
exec gdbserver 0.0.0.0:1234 /usr/bin/qemu-system-i386 -gdb stdio -xen-domid $DOMID -nodefaults -name qemu-3.0 -machine xenfv,max-ram-below-4g=0xf0000000 -m 1024 -drive file=/dev/xen/blktap-2/tapdev0,if=ide,index=0,media=disk,format=raw,readonly=off #-vnc 192.168.2.2:5900 $@
In another window, you can run gdb and do target remote localhost:1234.
TODO: QEMU mess and sv-interposer and qemu-dm-wrapper ... what is REALLY necessary?