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Diffstat (limited to 'README.md')
| -rw-r--r-- | README.md | 22 |
1 files changed, 16 insertions, 6 deletions
@@ -124,18 +124,28 @@ client/server model where basic tasks are performed. The server implements a device that can be programmed to trigger interrupts (INTx) to the client. This is done by writing the desired time in seconds since -Epoch. The server then trigger an eventfd-based IRQ and then a message-based +Epoch to BAR0. The server then triggers an eventfd-based IRQ and then a message-based one (in order to demonstrate how it's done when passing of file descriptors -isn't possible/desirable). +isn't possible/desirable). The device also works as memory storage: BAR1 can +be freely written to/read from by the host. + +Since this is a completely made up device, there's no kernel driver (yet). +[Client](./samples/client.c) implements a client that knows how to drive this +particular device (that would normally be QEMU + guest VM + kernel driver). The client excercises all commands in the vfio-user protocol, and then proceeds to perform live migration. The client spawns the destination server (this would -be normally done by `libvirt`) and then migrates the device state, before +be normally done by libvirt) and then migrates the device state, before switching entirely to the destination server. We re-use the source client instead of spawning a destination one as this is something libvirt/QEMU would -normally do. To spice things up, the client programmes the source server to -trigger an interrupt and then quickly migrates to the destination server; the -programmed interrupt is delivered by the destination server. +normally do. + +To spice things up, the client programs the source server to trigger an +interrupt and then migrates to the destination server; the programmed interrupt +is delivered by the destination server. Also, while the device is being live +migrated, the client spawns a thread that constantly writes to BAR1 in a tight +loop. This thread emulates the guest VM accessing the device while the main +thread (what would normally be QEMU) is driving the migration. Start the source server as follows (pick whatever you like for `/tmp/vfio-user.sock`): |