From: Thomas Gleixner <tglx@linutronix.de>
To: David Laight <David.Laight@ACULAB.COM>,
'Maximilian Luz' <luzmaximilian@gmail.com>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Sachi King <nakato@nakato.io>,
"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 15:01:48 +0200 [thread overview]
Message-ID: <87tun54gg3.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <e43d9a823c9e44bab0cdbf32a000c373@AcuMS.aculab.com>
David,
On Thu, May 13 2021 at 10:36, David Laight wrote:
>> -----Original Message-----
>> From: Maximilian Luz <luzmaximilian@gmail.com>
>> Sent: 13 May 2021 11:12
>> To: David Laight <David.Laight@ACULAB.COM>; Thomas Gleixner <tglx@linutronix.de>; Ingo Molnar
>> <mingo@redhat.com>; Borislav Petkov <bp@alien8.de>
>> Cc: H. Peter Anvin <hpa@zytor.com>; Sachi King <nakato@nakato.io>; x86@kernel.org; linux-
>> kernel@vger.kernel.org; stable@vger.kernel.org
>> Subject: Re: [PATCH] x86/i8259: Work around buggy legacy PIC
can you please fix your mail client and spare us the useless header
duplication in the reply?
> It is also worth noting that the probe code is spectacularly crap.
> It writes 0xff and then checks that 0xff is read back.
> Almost anything (including a failed PCIe read to the ISA bridge)
> will return 0xff and make the test pass.
unsigned char probe_val = ~(1 << PIC_CASCADE_IR);
outb(probe_val, PIC_MASTER_IMR);
new_val = inb(PIC_MASTER_IMR);
How is that writing 0xFF?
Thanks,
tglx
next prev parent reply other threads:[~2021-05-14 13:01 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 [this message]
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
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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