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| author | Gerd Hoffmann | 2022-07-11 11:44:36 +0200 |
|---|---|---|
| committer | Gerd Hoffmann | 2022-07-19 14:36:42 +0200 |
| commit | f3a445b68e7ed1d9fe14e3c92cfec38b1ac97331 (patch) | |
| tree | 48b6b1dfd346140a9270614ca8c1330dadf62295 /docs | |
| parent | usb/hcd-xhci: check slotid in xhci_wakeup_endpoint() (diff) | |
| download | qemu-f3a445b68e7ed1d9fe14e3c92cfec38b1ac97331.tar.gz qemu-f3a445b68e7ed1d9fe14e3c92cfec38b1ac97331.tar.xz qemu-f3a445b68e7ed1d9fe14e3c92cfec38b1ac97331.zip | |
usb: document guest-reset and guest-reset-all
Suggested-by: Michal Prívozník <mprivozn@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Message-Id: <20220711094437.3995927-2-kraxel@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/system/devices/usb.rst | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/docs/system/devices/usb.rst b/docs/system/devices/usb.rst index 872d916758..18e7c8b4d7 100644 --- a/docs/system/devices/usb.rst +++ b/docs/system/devices/usb.rst @@ -353,3 +353,32 @@ and also assign it to the correct USB bus in QEMU like this: -device usb-ehci,id=ehci \\ -device usb-host,bus=usb-bus.0,hostbus=3,hostport=1 \\ -device usb-host,bus=ehci.0,hostbus=1,hostport=1 + +``usb-host`` properties for reset behavior +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The ``guest-reset`` and ``guest-reset-all`` properties control +whenever the guest is allowed to reset the physical usb device on the +host. There are three cases: + +``guest-reset=false`` + The guest is not allowed to reset the (physical) usb device. + +``guest-reset=true,guest-resets-all=false`` + The guest is allowed to reset the device when it is not yet + initialized (aka no usb bus address assigned). Usually this results + in one guest reset being allowed. This is the default behavior. + +``guest-reset=true,guest-resets-all=true`` + The guest is allowed to reset the device as it pleases. + +The reason for this existing are broken usb devices. In theory one +should be able to reset (and re-initialize) usb devices at any time. +In practice that may result in shitty usb device firmware crashing and +the device not responding any more until you power-cycle (aka un-plug +and re-plug) it. + +What works best pretty much depends on the behavior of the specific +usb device at hand, so it's a trial-and-error game. If the default +doesn't work, try another option and see whenever the situation +improves. |