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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Borislav Petkov <bp@alien8.de>
Subject: Re: [GIT PULL] timer fixes
Date: Tue, 17 Dec 2019 12:43:46 -0800	[thread overview]
Message-ID: <CAHk-=whccvKaB-Fezv9w9XuZx4JDz4jDiJd+dATTj7yErhvpKQ@mail.gmail.com> (raw)
In-Reply-To: <20191217203506.GI2844@hirez.programming.kicks-ass.net>

On Tue, Dec 17, 2019 at 12:35 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> Pray.. the TSC MSR is still writable from SMM, so BIOS monkeys could
> still do what they've been doing for decades.

Sure. And the HPET is unreliable, so the checking causes issues.

Which one should we worry about?

> Also, what consititutes a 'modern' CPU?

I think anything that has TSC_STABLE set should likely be considered
more reliable than HPET.

Or whatever the bit is called. The "doesn't stop in idle" thing.

> > The HPET seems to get disabled on all the modern platforms, why do we
> > even have it enabled by default?
>
> These new ones yeah, cuz they wrecked HPET in PC10 :/

That's my point. HPET isn't _used_ by Windows, so it gets no testing,
so it will continue to have bugs.

At least the TSC is used.

I do agree about the whole SMM issue, but it seems less of a pain than
the HPET issue.

             Linus

  reply	other threads:[~2019-12-17 20:44 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-17 11:55 [GIT PULL] timer fixes Ingo Molnar
2019-12-17 19:14 ` Linus Torvalds
2019-12-17 19:30   ` Peter Zijlstra
2019-12-17 20:16     ` Linus Torvalds
2019-12-17 20:35       ` Peter Zijlstra
2019-12-17 20:43         ` Linus Torvalds [this message]
2019-12-17 20:54           ` Peter Zijlstra
2019-12-17 19:20 ` pr-tracker-bot
  -- strict thread matches above, loose matches on Subject: below --
2024-04-14  8:42 Ingo Molnar
2024-04-14 18:48 ` pr-tracker-bot
2024-04-07  8:03 Ingo Molnar
2024-04-07 16:44 ` pr-tracker-bot
2023-01-12 14:44 Ingo Molnar
2023-01-12 23:01 ` pr-tracker-bot
2022-08-13 10:25 Ingo Molnar
2022-08-13 16:25 ` Borislav Petkov
2022-08-13 20:27   ` Linus Torvalds
2022-08-14  8:57     ` Ingo Molnar
2022-08-14 12:41     ` Borislav Petkov
2022-08-14 17:24       ` Paul E. McKenney
2022-08-14 17:42         ` Borislav Petkov
2022-08-13 21:48 ` pr-tracker-bot
2020-12-27  9:26 Ingo Molnar
2020-12-27 17:27 ` pr-tracker-bot
2019-05-16 16:09 Ingo Molnar
2019-05-16 18:20 ` pr-tracker-bot
2019-04-20  7:45 Ingo Molnar
2019-04-20 19:25 ` pr-tracker-bot
2018-07-13 20:01 Ingo Molnar
2017-03-07 20:36 Ingo Molnar
2016-10-28  8:38 Ingo Molnar
2016-08-18 20:46 Ingo Molnar
2016-08-12 19:43 Ingo Molnar
2016-01-14 10:12 Ingo Molnar
2015-10-03 10:20 Ingo Molnar
2015-09-17  8:13 Ingo Molnar
2015-03-28 13:50 Ingo Molnar
2015-03-17 16:50 Ingo Molnar
2015-03-01 17:06 Ingo Molnar
2013-12-17 13:52 Ingo Molnar
2013-09-28 18:19 Ingo Molnar
2013-08-19  9:41 Ingo Molnar
2013-02-26 11:32 Ingo Molnar
2012-09-21 19:12 Ingo Molnar
2012-08-03 16:47 Ingo Molnar
2011-12-20 19:25 Ingo Molnar
2011-12-05 19:00 Ingo Molnar
2011-06-19  8:51 Ingo Molnar
2011-06-13  9:55 Ingo Molnar
2011-06-06 19:10 [GIT pull] " Thomas Gleixner
2011-05-20 17:52 Thomas Gleixner
2011-04-19 16:03 [GIT PULL] " Ingo Molnar
2011-04-16 10:09 Ingo Molnar
2011-04-07 17:42 Ingo Molnar
2011-02-06 12:06 Ingo Molnar
2011-01-24 13:24 Ingo Molnar
2010-11-26 13:40 Ingo Molnar
2010-03-26 15:34 Ingo Molnar
2009-12-18 18:49 Ingo Molnar
2009-10-08 18:35 Ingo Molnar
2009-08-25 18:04 Ingo Molnar
2009-06-26 19:03 Ingo Molnar
2009-04-09 15:43 Ingo Molnar
2009-01-30 23:07 [git pull] " Ingo Molnar
2009-01-26 17:21 Ingo Molnar
2009-01-06 16:18 Ingo Molnar
2008-12-04 20:52 Ingo Molnar
2008-11-11 18:47 Ingo Molnar
2008-09-23 19:41 Ingo Molnar
2008-09-17  9:59 Ingo Molnar
2008-08-25 17:52 Ingo Molnar
2008-08-22 12:24 Ingo Molnar
2008-07-24 15:18 Ingo Molnar

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