On Thu, Nov 25, 2021 at 05:36:29PM +0530, Ani Sinha wrote: > x-native-hotplug property, when used in order to disable HPC bit on the PCIE > root ports, can lead to unexpected results from the guest operating system. > Users are strongly advised not to touch this property in order to manipulte > the > HPC bit. Add a word of caution in the pcie.txt doc file to document this. > > Signed-off-by: Ani Sinha <a...@anisinha.ca>
Do we want to generally document this for all "x-" options? > --- > docs/pcie.txt | 17 ++++++++++++++++- > 1 file changed, 16 insertions(+), 1 deletion(-) > > diff --git a/docs/pcie.txt b/docs/pcie.txt > index 89e3502075..e1f99f725f 100644 > --- a/docs/pcie.txt > +++ b/docs/pcie.txt > @@ -262,11 +262,26 @@ PCI Express Root Ports (and PCI Express Downstream > Ports). > Port, which may come handy for hot-plugging another device. > > > -5.3 Hot-plug example: > +5.2 Hot-plug example: > Using HMP: (add -monitor stdio to QEMU command line) > device_add <dev>,id=<id>,bus=<PCI Express Root Port Id/PCI Express > Downstream Port Id/PCI-PCI Bridge Id/> > > > +5.3 A word of caution using hotplug on PCI Express Root Ports: > +Starting Qemu version 6.2, PCI Express Root ports have a property > +"x-native-hotplug" ("native-hotplug" for Qemu version 6.1), that can be used > to > +enable or disable hotplug on that port. For example: > + > +-device pcie-root-port,x-native-hotplug=off,... etc. > + > +The "x-" prefix indicates that this property is highly experimental and can > +lead to unexpected results from the guest operating system if users try to > use > +it to alter the native hotplug on the port. It also means that the property > +name and its behavior is liable to change in the future and is not expected > to > +be stable across Qemu versions. Therefore, end users are advised not to > change > +the value of this option from its default set value or use it in the Qemu > +command line. > + > 6. Device assignment > ==================== > Host devices are mostly PCI Express and should be plugged only into > -- > 2.25.1