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From: Thomas Gleixner <tglx@linutronix.de>
To: Maximilian Luz <luzmaximilian@gmail.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Sachi King <nakato@nakato.io>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	David Laight <David.Laight@aculab.com>
Cc: "x86\@kernel.org" <x86@kernel.org>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"stable\@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH] x86/i8259: Work around buggy legacy PIC
Date: Mon, 17 May 2021 20:40:10 +0200	[thread overview]
Message-ID: <87a6otfblh.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <087c418e-53fb-b3a6-0d9b-e738e4c821c7@gmail.com>

Max,

On Sat, May 15 2021 at 00:47, Maximilian Luz wrote:
> I believe the theory was that, while the PIC is advertised in ACPI, it
> might be expected to not be used and only present for some legacy reason
> (therefore untested and buggy). Which I believe led to the question
> whether we shouldn't prefer IOAPIC on systems like that in general. So I
> guess it comes down to how you define "systems like that". By Tomas'
> comment, I guess it should be possible to implement this as "systems
> that should prefer IOAPIC over legacy PIC" quirk.
>
> I guess all modern machines should have an IOAPIC, so it might also be
> preferable to expand that definition, maybe over time and with enough
> testing.

I just double checked and we actually can boot just fine without the
PIC even when it is advertised, but disfunctional.

Can you please add "apic=verbose" to the kernel command line and provide
full dmesg output for a kernel w/o your patch and one with your patch
applied?

Thanks,

        tglx



  reply	other threads:[~2021-05-17 18:40 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-12 21:04 [PATCH] x86/i8259: Work around buggy legacy PIC Maximilian Luz
2021-05-13  8:10 ` David Laight
2021-05-13 10:11   ` Maximilian Luz
2021-05-13 10:36     ` David Laight
2021-05-14 13:01       ` Thomas Gleixner
2021-05-14 13:13         ` David Laight
2021-05-14 16:19           ` Ingo Molnar
2021-05-14 19:41       ` Sachi King
2021-05-14 10:51         ` David Laight
2021-05-14 11:58         ` Maximilian Luz
2021-05-14 17:32           ` Thomas Gleixner
2021-05-14 17:35             ` H. Peter Anvin
2021-05-14 22:47               ` Maximilian Luz
2021-05-17 18:40                 ` Thomas Gleixner [this message]
2021-05-17 19:25                   ` Maximilian Luz
2021-05-17 23:27                     ` Thomas Gleixner
2021-05-18  8:28                       ` Andy Shevchenko
2021-05-18 19:58                       ` Sachi King
2021-05-18 15:45                         ` Thomas Gleixner
2021-05-14 13:44     ` Thomas Gleixner
2021-05-14 16:12       ` David Laight
2021-05-14 17:28         ` H. Peter Anvin

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