From: "Maciej W. Rozycki" <macro@linux-mips.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: hpa@zytor.com, Andrew Cooper <andrew.cooper3@citrix.com>,
LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, Jan Kiszka <jan.kiszka@siemens.com>,
James Morris <jmorris@namei.org>,
David Howells <dhowells@redhat.com>,
Matthew Garrett <mjg59@google.com>,
Josh Boyer <jwboyer@redhat.com>,
Zhenzhong Duan <zhenzhong.duan@oracle.com>,
Steve Wahl <steve.wahl@hpe.com>,
Mike Travis <mike.travis@hpe.com>,
Dimitri Sivanich <dimitri.sivanich@hpe.com>,
Arnd Bergmann <arnd@arndb.de>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Giovanni Gherdovich <ggherdovich@suse.cz>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Len Brown <len.brown@intel.com>,
Kees Cook <keescook@chromium.org>,
Martin Molnar <martin.molnar.programming@gmail.com>,
Pingfan Liu <kernelfans@gmail.com>,
jailhouse-dev@googlegroups.com
Subject: Re: [PATCH] x86/smpboot: Remove 486-isms from the modern AP boot path
Date: Wed, 1 Apr 2020 00:35:16 +0100 (BST) [thread overview]
Message-ID: <alpine.LFD.2.21.2004010001460.3939520@eddie.linux-mips.org> (raw)
In-Reply-To: <87r1xgxzy6.fsf@nanos.tec.linutronix.de>
On Wed, 25 Mar 2020, Thomas Gleixner wrote:
> >>@@ -1118,7 +1121,7 @@ static int do_boot_cpu(int apicid, int cpu,
> >>struct task_struct *idle,
> >> }
> >> }
> >>
> >>- if (x86_platform.legacy.warm_reset) {
> >>+ if (!APIC_INTEGRATED(boot_cpu_apic_version)) {
> >> /*
> >> * Cleanup possible dangling ends...
> >> */
> >
> > We don't support SMP on 486 and haven't for a very long time. Is there
> > any reason to retain that code at all?
>
> Not that I'm aware off.
For the record: this code is for Pentium really, covering original P5
systems, which lacked integrated APIC, as well as P54C systems that went
beyond dual (e.g. ALR made quad-SMP P54C systems). They all used external
i82489DX APICs for SMP support. Few were ever manufactured and getting
across one let alone running Linux might be tough these days. I never
managed to get one for myself, which would have been helpful for
maintaining this code.
Even though we supported them by spec I believe we never actually ran MP
on any 486 SMP system (Alan Cox might be able to straighten me out on
this); none that I know of implemented the MPS even though actual hardware
might have used the APIC architecture. Compaq had its competing solution
for 486 and newer SMP, actually deployed, the name of which I long forgot.
We never supported it due to the lack of documentation combined with the
lack of enough incentive for someone to reverse-engineer it.
FWIW,
Maciej
next prev parent reply other threads:[~2020-03-31 23:35 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 10:14 Andrew Cooper
2020-03-25 10:17 ` hpa
2020-03-25 14:37 ` Thomas Gleixner
2020-03-31 23:35 ` Maciej W. Rozycki [this message]
2020-04-01 10:23 ` David Laight
2020-04-01 13:26 ` Maciej W. Rozycki
2020-04-01 22:30 ` Andrew Cooper
2020-04-01 23:32 ` Maciej W. Rozycki
2020-03-31 17:58 ` [PATCH v2] " Andrew Cooper
2020-03-31 22:23 ` Brian Gerst
2020-03-31 22:44 ` Andrew Cooper
2020-03-31 22:53 ` Brian Gerst
2020-04-01 9:22 ` Andrew Cooper
2020-04-01 11:39 ` Brian Gerst
2020-04-01 12:14 ` Andrew Cooper
2020-04-01 14:38 ` Brian Gerst
2020-04-01 14:47 ` Andrew Cooper
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.LFD.2.21.2004010001460.3939520@eddie.linux-mips.org \
--to=macro@linux-mips.org \
--cc=andrew.cooper3@citrix.com \
--cc=arnd@arndb.de \
--cc=bp@alien8.de \
--cc=dhowells@redhat.com \
--cc=dimitri.sivanich@hpe.com \
--cc=ggherdovich@suse.cz \
--cc=hpa@zytor.com \
--cc=jailhouse-dev@googlegroups.com \
--cc=jan.kiszka@siemens.com \
--cc=jmorris@namei.org \
--cc=jwboyer@redhat.com \
--cc=keescook@chromium.org \
--cc=kernelfans@gmail.com \
--cc=len.brown@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=martin.molnar.programming@gmail.com \
--cc=mike.travis@hpe.com \
--cc=mingo@redhat.com \
--cc=mjg59@google.com \
--cc=peterz@infradead.org \
--cc=rafael.j.wysocki@intel.com \
--cc=steve.wahl@hpe.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
--cc=zhenzhong.duan@oracle.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome