missed. In other words, if a new request for an IPI is sent while the
previous request is being handled but the IPI is not cleared yet, the
clearing of the previous IPI request also clears the new one and the
handling is missed.
There are only three MP interrupt controllers in ARM now. Two of them are
fixed by this change, the third one is correct, probably only just by
accident. The fix is minimalistic as new interrupt framework is awaited.
It was debugged on RPi2 where missing IPI handling together with SCHED_ULE
led to situation in which tdq_ipipending was not cleared and so IPI_PREEMPT
was stopped to be sent. Various odditys were found related to slow system
response time like various events timed out, and slow console response.
Submitted by: Svatopluk Kraus <onwahe@gmail.com>
Reviewed by: loos, kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D3722
to check the status property in their probe routines.
Simplebus used to only instantiate its children whose status="okay"
but that was improper behavior, fixed in r261352. Now that it doesn't
check anymore and probes all its children; the children all have to
do the check because really only the children know how to properly
interpret their status property strings.
Right now all existing drivers only understand "okay" versus something-
that's-not-okay, so they all use the new ofw_bus_status_okay() helper.
MSI are implemented via software interrupt. PCIe cards will write
into software interrupt register which will cause inbound shared
interrupt which will be interpreted as a MSI.
Obtained from: Marvell, Semihalf
