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From: Thomas Gleixner <tglx@linutronix.de>
To: Maximilian Luz <luzmaximilian@gmail.com>,
	Sachi King <nakato@nakato.io>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	David Laight <David.Laight@aculab.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	"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: Fri, 14 May 2021 19:32:54 +0200	[thread overview]
Message-ID: <87im3l43w9.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <5c08541a-2615-f075-a189-0462f1005007@gmail.com>

On Fri, May 14 2021 at 13:58, Maximilian Luz wrote:
> On 5/14/21 9:41 PM, Sachi King wrote:
> I'd assume that _some_ sort of interrupt setup is done by the BIOS/UEFI.
> The UEFI on those devices is fairly well-featured, with touch support
> via SPI and all. Furthermore, keyboard (also supported in the device's
> UEFI) is handled via a custom UART protocol. Unless they rely on polling
> for all of that, I believe they'd have to set up some interrupts.

Polling would be truly surprising.

> Although, as you mention later on, that could also be handled via the
> IOAPIC and the PIC is actually not supposed to be used. Maybe some
> legacy component that never got tested and just broke with some new
> hardware/firmware revision without anyone noticing? And since Linux
> still seems to rely on that, we might be the first to notice.

That's a valid assumption. As I said, we can make IOAPIC work even w/o
PIC. I'll have a look how much PIC assumptions are still around.

Thanks,

        tglx

  reply	other threads:[~2021-05-14 17:32 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 [this message]
2021-05-14 17:35             ` H. Peter Anvin
2021-05-14 22:47               ` Maximilian Luz
2021-05-17 18:40                 ` Thomas Gleixner
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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