Re: kernel/microcode.c error from new 64bit code

From: Pavel Machek
Date: Sat Feb 21 2004 - 12:37:36 EST


Hi!

> > > + wrmsr(MSR_IA32_UCODE_WRITE,
> > > + (unsigned long) uci->mc->bits,
> > > + (unsigned long) uci->mc->bits >> 16 >> 16);
> > ~~~~~~~~~~~~
> >
> > I see what you are doing, but this is evil. At least comment /* ">> 32"
> > is undefined on i386 */ ?
>
> Sorry, but you're wrong.
>
> ">> 32" is underfined PERIOD! It has nothing to do with x86, it's a C
> standards issue. It's undefined on any 32-bit architecture. (shifting by
> the wordsize or bigger is simply not a defined C operation).

Yep, that is what I wanted to say. [This driver only has meaning for
i386 and ia32e => if we have 32-bit architecture, it must be i386.]

> The above is not evil. The above is the standard way of doing this in C if
> you know the word-size is 32-bits or bigger.

I'm just afraid that someone will mail you a patch replacing that with
>> 32 and you'll overlook it.

Pavel
--
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]
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