From: Marek Marczykowski-Górecki Date: Tue, 19 May 2020 01:54:45 +0000 (-0400) Subject: Document ioemu MiniOS stubdomain protocol X-Git-Tag: archive/raspbian/4.14.0+80-gd101b417b7-1+rpi1^2~63^2~246 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=c7c145470168c67ba45911370bd6902917e59da5;p=xen.git Document ioemu MiniOS stubdomain protocol Add documentation based on reverse-engineered toolstack-ioemu stubdomain protocol. Signed-off-by: Marek Marczykowski-Górecki Signed-off-by: Jason Andryuk Acked-by: Ian Jackson --- diff --git a/docs/misc/stubdom.txt b/docs/misc/stubdom.txt index 882a18cab4..64c77d9b64 100644 --- a/docs/misc/stubdom.txt +++ b/docs/misc/stubdom.txt @@ -23,6 +23,59 @@ and https://wiki.xen.org/wiki/Device_Model_Stub_Domains for more information on device model stub domains +Toolstack to MiniOS ioemu stubdomain protocol +--------------------------------------------- + +This section describe communication protocol between toolstack and +qemu-traditional running in MiniOS stubdomain. The protocol include +expectations of both qemu and stubdomain itself. + +Setup (done by toolstack, expected by stubdomain): + - Block devices for target domain are connected as PV disks to stubdomain, + according to configuration order, starting with xvda + - Network devices for target domain are connected as PV nics to stubdomain, + according to configuration order, starting with 0 + - if graphics output is expected, VFB and VKB devices are set for stubdomain + (its backend is responsible for exposing them using appropriate protocol + like VNC or Spice) + - other target domain's devices are not connected at this point to stubdomain + (may be hot-plugged later) + - QEMU command line (space separated arguments) is stored in + /vm//image/dmargs xenstore path + - target domain id is stored in /local/domain//target xenstore path +?? - bios type is stored in /local/domain//hvmloader/bios + - stubdomain's console 0 is connected to qemu log file + - stubdomain's console 1 is connected to qemu save file (for saving state) + - stubdomain's console 2 is connected to qemu save file (for restoring state) + - next consoles are connected according to target guest's serial console configuration + +Startup: +1. PV stubdomain is started with ioemu-stubdom.gz kernel and no initrd +2. stubdomain initialize relevant devices +3. stubdomain signal readiness by writing "running" to /local/domain//device-model//state xenstore path +4. now stubdomain is considered running + +Runtime control (hotplug etc): +Toolstack can issue command through xenstore. The sequence is (from toolstack POV): +1. Write parameter to /local/domain//device-model//parameter. +2. Write command to /local/domain//device-model//command. +3. Wait for command result in /local/domain//device-model//state (command specific value). +4. Write "running" back to /local/domain//device-model//state. + +Defined commands: + - "pci-ins" - PCI hot plug, results: + - "pci-inserted" - success + - "pci-insert-failed" - failure + - "pci-rem" - PCI hot remove, results: + - "pci-removed" - success + - ?? + - "save" - save domain state to console 1, results: + - "paused" - success + - "continue" - resume domain execution, after loading state from console 2 (require -loadvm command argument), results: + - "running" - success + + + PV-GRUB =======