[Skiboot] [PATCH] hw/bt: Add backend interface to disable ipmi message retry option

[Stewart Smith]

Vasant Hegde <hegdevasant at linux.vnet.ibm.com> writes:
> During boot OPAL makes IPMI_GET_BT_CAPS call to BMC to get BT interface
> capabilities which includes IPMI message max resend count, message
> timeout, etc,. Most of the time OPAL gets response from BMC within
> specified timeout. In some corner cases (like mboxd daemon reset in BMC,
> BMC reboot, etc) OPAL may not get response within timeout period. In
> such scenarios, OPAL resends message until max resend count reaches.
>
> OPAL uses synchronous IPMI message (ipmi_queue_msg_sync()) for few
> operations like flash read, write, etc. Thread will wait in OPAL until
> it gets response from BMC. In some corner cases like BMC reboot, thread
> may wait in OPAL for long time (more than 20 seconds) and results in
> kernel hardlockup.
>
> This patch introduces new interface to disable message resend option. We
> will disable message resend option for synchrous message. This will
> greatly reduces kernel hardlock up issues.
>
> This is short term fix. Long term solution is to convert all synchronous
> messages to asynhrounous one.

Agree.

In the meantime, merged to master as of
01f977c33d46f35ae6735c874d415a793d7bd9af.

(again, probably needs to go to stable, but will let you poke at that :)

-- 
Stewart Smith
OPAL Architect, IBM.