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From: "Arnd Bergmann" <arnd@arndb.de>
To: "kernel test robot" <oliver.sang@intel.com>
Cc: oe-lkp@lists.linux.dev, "kernel test robot" <lkp@intel.com>,
	linux-kernel@vger.kernel.org, "Ingo Molnar" <mingo@kernel.org>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"John Stultz" <jstultz@google.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Stephen Boyd" <sboyd@kernel.org>,
	"Borislav Petkov" <bp@alien8.de>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [linus:master] [x86/cpu]  f388f60ca9: BUG:soft_lockup-CPU##stuck_for#s![swapper:#]
Date: Sun, 27 Apr 2025 14:07:09 +0200	[thread overview]
Message-ID: <963683ea-eaba-4430-bd8a-1b11affe104a@app.fastmail.com> (raw)
In-Reply-To: <aA3FL6e1HVAw1J+w@xsang-OptiPlex-9020>

On Sun, Apr 27, 2025, at 07:48, Oliver Sang wrote:
> On Thu, Apr 24, 2025 at 09:59:38AM +0200, Arnd Bergmann wrote:
>> 
>> Thanks for confirming. So a 486-targeted kernel still passes
>> your tests on modern hardware if we force TSC and CX8 to
>> be enabled, but the boot fails if the options are turned
>> off in Kconfig (though available in emulated hardware).
>> 
>> To be completely sure, you could re-run the same test with
>> just one of these enabled, but I'm rather sure that the TSC
>> is the root cause.
>
> just FYI. we rerun the tests. if only enable X86_TSC, the config diff is

...
> the various issues still exists:

>
> if only enable X86_CMPXCHG64:
...
> various issues gone:

Interesting, so cx8 was indeed a problem. I would still assume
that TSC caused the boot panic I cited, but it looks like CX8
caused all the other symptoms.

At the minimum this strengthens the case for the consensus of
dropping support for all pre-586 cores.

Thanks a lot for confirming! 

      Arnd

  reply	other threads:[~2025-04-27 12:07 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-21  8:12 kernel test robot
2025-04-22 10:16 ` Arnd Bergmann
2025-04-24  2:12   ` Oliver Sang
2025-04-24  7:59     ` Arnd Bergmann
2025-04-24 16:07       ` Linus Torvalds
2025-04-24 17:54         ` [RFC PATCH 0/15] x86: Remove support for TSC-less and CX8-less CPUs Ingo Molnar
2025-04-24 18:01           ` Ingo Molnar
2025-04-24 21:27           ` Arnd Bergmann
2025-04-25  7:40             ` Ingo Molnar
2025-04-25  9:30               ` Arnd Bergmann
2025-04-26  4:06         ` [linus:master] [x86/cpu] f388f60ca9: BUG:soft_lockup-CPU##stuck_for#s![swapper:#] H. Peter Anvin
2025-04-27  5:48       ` Oliver Sang
2025-04-27 12:07         ` Arnd Bergmann [this message]
2025-04-27 16:39         ` Linus Torvalds
2025-04-27 21:19           ` H. Peter Anvin

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