Date: Sat, 30 Nov 1996 11:56:05 -0700 From: Steve Passe <smp@csn.net> To: Erich Boleyn <erich@uruk.org> Cc: Peter Wemm <peter@spinner.dialix.com>, smp@freebsd.org Subject: Re: SMP-current hang problems. Message-ID: <199611301856.LAA07855@clem.systemsix.com> In-Reply-To: Your message of "Sat, 30 Nov 1996 10:20:01 PST." <E0vTu1B-000831-00@uruk.org>
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Hi, >Without APIC_IO, I got messages like the above for all 3 of the other CPUs >in my box. Pretty cool! Syscons was screwed up here, so I don't think >it is just an "APIC_IO" problem. I could bang on the keyboard for a long >time and it kept going. > >With APIC_IO, I got one message like the above for "CPU #3", but after >the "Starting Scheduling..." part, it said "SMP: freezing CPU #3", then >no more SMP CPU booting messages. Syscons was screwed up here in nice to hear some good news for a change! there is a known race condition in the order in which APs are started. Specifically they are all started at low level in mpboot.s and held by the sem "bootlock". The 1st AP is released by the BSP once the system is running processes. Each AP then releases another as it "enters" its own process space. The offending code is in kern/init_main.c, smp_idleloop(), which ONLY works if APs happen to start in numeric order. Peter was doing the fix, perhaps he should release this now if it won't confuse the "hang" situation too much. --- >With APIC_IO, I got one message like the above for "CPU #3", but after >the "Starting Scheduling..." part, it said "SMP: freezing CPU #3", then >no more SMP CPU booting messages. Syscons was screwed up here in >apparently the exact same fashion. If I banged on the keyboard too much, >it would lock up. as described above, probably just the race on CPU numbers. If you rebooted several times it might work, and there are no guarantees that the non APIC_IO version will work every time. --- >I think I'm more interested in fixing syscons than regressing it and >a bunch of other files, perhaps with unpredictable results. > >More later. (is there anything specific I should try?) I haven't heard anything lately on the syscons problems, it just "went away" for my system so I haven't been able to attack it. If you can gain any insight on this one it would be greatly appreciated! -- Steve Passe | powered by smp@csn.net | FreeBSD -----BEGIN PGP PUBLIC KEY BLOCK----- Version: 2.6.2 mQCNAzHe7tEAAAEEAM274wAEEdP+grIrV6UtBt54FB5ufifFRA5ujzflrvlF8aoE 04it5BsUPFi3jJLfvOQeydbegexspPXL6kUejYt2OeptHuroIVW5+y2M2naTwqtX WVGeBP6s2q/fPPAS+g+sNZCpVBTbuinKa/C4Q6HJ++M9AyzIq5EuvO0a8Rr9AAUR tBlTdGV2ZSBQYXNzZSA8c21wQGNzbi5uZXQ+ =ds99 -----END PGP PUBLIC KEY BLOCK-----
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