[haiku-bugs] Re: [Haiku] #8085: SMI storm on USB handover on AMD 970/SB950 AMD AM3+ UEFI motherboard

#8085: SMI storm on USB handover on AMD 970/SB950 AMD AM3+ UEFI motherboard
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   Reporter:  kallisti5      |      Owner:  mmlr
       Type:  bug            |     Status:  in-progress
   Priority:  normal         |  Milestone:  R1
  Component:  System/Kernel  |    Version:  R1/Development
 Resolution:                 |   Keywords:  SB950,UEFI, AHCI, APIC, IRQ
 Blocked By:                 |   Blocking:
Has a Patch:  1              |   Platform:  All
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Comment (by mmlr):

 While I agree that disabling all interrupts may very well be a problem,
 not disabling them at all is not an option. The reason why they are
 disabled is that we don't want to get interrupts while we haven't set up
 an interrupt handler yet and therefore would cause an interrupt storm on
 our end when the handover happens and doesn't clear the interrupts. Hence
 disabling everything besides the ownership change would possibly work. The
 sequence itself has been carefully crafted, so please don't just shoot
 into it (it is mostly the same as FreeBSD as the comment there suggests).
 Checking for the run state, additionally to the interrupt routing state,
 may make sense as well.

 Regarding "many cases we don't handle": Quite a few of these aren't
 relevant as we always reset the controller. And, as the comment there
 suggests, this has been noticed as needed on some controllers at least, so
 just throwing that out isn't necessarily a good idea IMO.

-- 
Ticket URL: <http://dev.haiku-os.org/ticket/8085#comment:15>
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