Re: [PATCH 9/11] Panic delay fix

From: "Dmitry Torokhov" <dmitry.torokhov@gmail.com>
To: "Zachary Amsden" <zach@vmware.com>
Cc: "Rusty Russell" <rusty@rustcorp.com.au>,
	"Pavel Machek" <pavel@ucw.cz>, "Andi Kleen" <ak@muc.de>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"Andrew Morton" <akpm@osdl.org>,
	"Jeremy Fitzhardinge" <jeremy@goop.org>,
	"Chris Wright" <chrisw@sous-sol.org>
Subject: Re: [PATCH 9/11] Panic delay fix
Date: Thu, 8 Feb 2007 16:37:31 -0500	[thread overview]
Message-ID: <d120d5000702081337j3eecbc41r4e9e44014b7cedfe@mail.gmail.com> (raw)
In-Reply-To: <45CB9588.50300@vmware.com>

On 2/8/07, Zachary Amsden <zach@vmware.com> wrote:
> Dmitry Torokhov wrote:
> >
> > However I am not really fond of idea of adding constructs like this
> > all over the code:
> >
> > #define USE_REAL_TIME_DELAY_I_REALLY_MEAN_IT_THIS_TIME_I_SWEAR
> >
> > as the time passes... Drivers should be blissfully ignorant of being
> > run on virtual hardware.
>
> I agree in general, but there are two uses for this ugly construct.  One
> is for drivers and isolated sections of code which actually interact
> with the real world.  They need real time delays.  The only two examples
> so far are SMP coprocessor bootstrapping and blinking LEDs with a
> recognizable frequency.  I don't expect many more to show up.
>

I am pretty sure that using that construct inside of i8042 is wrong -
the host OS should handle hardware access/delay issues. Have you
verified that fixing kerne/panic.c to call i8042_panic_blink once per
1 ms (as it happens on native running kernel) does not produce the
desired blinking?

-- 
Dmitry