On 04/28/18 at 08:56am, Dave Young wrote: > On 04/27/18 at 04:12pm, Bjorn Helgaas wrote: > > [+cc Eric, Vivek, kexec list] > > > > On Fri, Apr 27, 2018 at 03:34:30PM -0400, Sinan Kaya wrote: > > > On 4/27/2018 3:22 PM, Bjorn Helgaas wrote: > > > > Sinan mooted the idea of using a "no-wait" path of sending the "don't > > > > generate hotplug interrupts" command. I think we should work on this > > > > idea a little more. If we're shutting down the whole system, I can't > > > > believe there's much value in *anything* we do in the pciehp_remove() > > > > path. > > > > > > > > Maybe we should just get rid of pciehp_remove() (and probably > > > > pcie_port_remove_service() and the other service driver remove methods) > > > > completely. That dates from when the service drivers could be modules that Hmm, if it is the remove() method then kexec does not use it. kexec use the shutdown() method instead. I missed this details when I replied. > > > > could be potentially unloaded, but unloading them hasn't been possible for > > > > years. > > > > > > Shutdown path is also used for kexec. Leaving hotplug interrupts > > > pending is dangerous for the newly loaded kernel as it leaves > > > spurious interrupts during the new kernel boot. > > > > > > I think we should always disable the hotplug interrupt on shutdown. > > > We might think of not waiting for command-completion as a > > > middle-ground or go to polling path instead of interrupts all the > > > time. > > > > Ah, I forgot about the kexec path. The kexec path is used for > > crashdump, too, so ideally the newly-loaded kernel would defend itself > > when possible so it doesn't depend on the original kernel doing things > > correctly. > > It is true for kdump. But kexec needs device shutdown. > > > > > Seems like this question of whether to do things in the original > > kernel or the kexec-ed kernel comes up periodically, but I can never > > remember a definitive answer. My initial reaction is that it'd be > > nice if we didn't have to do *any* shutdown in the original kernel, > > but I'm sure there are reasons that's not practical. > > Devices sometimes assume it is in a good state initialized in firmware boot > phase, so we need a shutdown in 1st kernel so that kexec kernel can boot > correctly for those devices. For kdump since kernel already panicked > and it is not reliable so we do as less as we can in the 1st kernel > crash path, but there are some special handling for kdump in various drivers > to reset the devices in 2nd kernel, eg. when it see "reset_devices" kernel parameter. > > > > > I copied Eric (kexec maintainer) and Vivek (contact listed in > > Documentation/kdump/kdump.txt) in case they have suggestions or would > > consider some sort of Documentation/ update. > > > > Bjorn > > > > _______________________________________________ > > kexec mailing list > > kexec@xxxxxxxxxxxxxxxxxxx > > http://lists.infradead.org/mailman/listinfo/kexec > > Thanks > Dave > > _______________________________________________ > kexec mailing list > kexec@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/kexec _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
