From: Rusty Russell <rusty@rustcorp.com.au>
To: Pavel Machek <pavel@ucw.cz>
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Booting when CPUs fail to come up.
Date: Sun, 22 Feb 2004 12:43:04 +1100 [thread overview]
Message-ID: <20040222022340.E9D132C361@lists.samba.org> (raw)
In-Reply-To: Your message of "Sat, 21 Feb 2004 14:33:59 BST." <20040221133359.GA339@elf.ucw.cz>
In message <20040221133359.GA339@elf.ucw.cz> you write:
> Hi!
>
> > > > I recently played with setting a bit in cpu_possible_map that wasn't
> > > > in cpu_online_map: this can happen without hotplug CPU when a CPU
> > > > fails to boot, for example.
> > >
> > > Is it safe to continue when one cpu is apparently malfunctioning?
> >
> > Well, patch was overzealous and no longer required.
> >
> > But we shouldn't crash when this happens just because a CPU didn't
> > come up.
>
> I still do not agree.
You're entitled. However, on x86 we booted before when a secondary
CPU didn't come up, and the patch was designed to ensure that we still
did so.
> You have a system you tried to kick CPU #13 alive, and something very
> wrong happened, CPU #13 did not come up. It is there, has full access
> to memory, it is probably running some kind of program....
No, it's possible, but not online. This actually happens on archs
where you have hotplug cpus, as well as x86 boot failures.
> I'd not dare mount disks read-write in such situation and I believe
> crashing early is actually right thing to do.
Sure, send a patch for x86 to do that, and we can discuss that. I'm
not going to break existing behavior by stealth though.
Rusty.
--
Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
prev parent reply other threads:[~2004-02-22 2:23 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-13 7:57 Rusty Russell
2004-02-20 16:10 ` Pavel Machek
2004-02-21 0:37 ` Rusty Russell
2004-02-21 13:33 ` Pavel Machek
2004-02-22 1:43 ` Rusty Russell [this message]
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