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agent: re-scan pci bus to discover hidden devices #139

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sboeuf merged 1 commit into from
Oct 27, 2017
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agent: re-scan pci bus to discover hidden devices #139

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8 changes: 8 additions & 0 deletions agent.go
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Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,8 @@ const (
logLevelFlag = optionPrefix + "log"
defaultLogLevel = logrus.InfoLevel
cannotGetTimeMsg = "Failed to get time for event %s:%v"
pciBusRescanFile = "/sys/bus/pci/rescan"
pciBusMode = 0220
)

var capsList = []string{
Expand Down Expand Up @@ -1060,6 +1062,12 @@ func addMounts(config *configs.Config, fsmaps []hyper.Fsmap) error {
func newContainerCb(pod *pod, data []byte) error {
var payload hyper.NewContainer

// re-scan PCI bus
// looking for hidden devices
if err := ioutil.WriteFile(pciBusRescanFile, []byte("1"), pciBusMode); err != nil {
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@mcastelino mcastelino Oct 23, 2017

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@devimc In the other PR you are reusing the pci slots. Not sure if a slot will ever be reused (block device unplug followed by a plug in the real world with virtcontainers). However if that does happen, what happens to the mount points?

Also how do we know when the rescan is complete?

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@devimc devimc Oct 25, 2017 •
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@mcastelino pci slots can be reused once it's free

what happens to the mount points?

There is still missing that part, in qemu <= 2.9 Q35 PCI devices must be removed manually, I guess we have to implement an extra command in the agent to clean up unplugged devices

Also how do we know when the rescan is complete?

it is a blocking IO operation, process will not continue until all PCI buses are re-scanned

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@mcastelino mcastelino Oct 27, 2017

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@devimc will the pci slot reuse happen in the real world. Do we support removing a container from a POD?

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@devimc devimc Oct 27, 2017

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not sure if we can remove a container from a POD, but we can unplug devices from bridges.
we could reuse that slot to hot plug another device if we need it since we have a limitation in the number of devices per bridge.

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@mcastelino mcastelino Oct 27, 2017

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@devimc so when will we ever unplug a device? I cannot think of a case. Which means we are ok for now and need no special logic or unmount/remount.

agentLog.WithError(err).Warnf("Could not rescan PCI bus")
}

if pod.running == false {
return fmt.Errorf("Pod not started, impossible to run a new container")
}
Expand Down