linux-kernel - RE: [PATCH] x86/i8259: Work around buggy legacy PIC

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Message-ID: <9b70d8113c084848b8d9293c4428d71b@AcuMS.aculab.com>
Date:   Thu, 13 May 2021 08:10:54 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Maximilian Luz' <luzmaximilian@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>
CC:     "H. Peter Anvin" <hpa@...or.com>, Sachi King <nakato@...ato.io>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: RE: [PATCH] x86/i8259: Work around buggy legacy PIC

From: Maximilian Luz
> Sent: 12 May 2021 22:05
> 
> The legacy PIC on the AMD variant of the Microsoft Surface Laptop 4 has
> some problems on boot. For some reason it consistently does not respond
> on the first try, requiring a couple more tries before it finally
> responds.

That seems very strange, something else must be going on that causes the grief.
The 8259 will be built into to the one of the cpu support chips.
I can't imagine that requires anything special.

It's not as though you have a real 8259 - which even a 286 can
break the inter-cycle recovery on (with the circuit from the
application note).

	David

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