From: Linus Torvalds <torvalds@osdl.org>
To: Pavel Machek <pavel@suse.cz>
Cc: Stephen Hemminger <shemminger@osdl.org>,
ak@suse.de, linux-kernel@vger.kernel.org
Subject: Re: kernel/microcode.c error from new 64bit code
Date: Sat, 21 Feb 2004 09:18:14 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.58.0402210914530.3301@ppc970.osdl.org> (raw)
In-Reply-To: <20040221141608.GB310@elf.ucw.cz>
On Sat, 21 Feb 2004, Pavel Machek wrote:
>
> > + 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).
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.
Linus
next prev parent reply other threads:[~2004-02-21 17:13 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-18 22:52 Stephen Hemminger
2004-02-18 23:08 ` Linus Torvalds
2004-02-18 23:21 ` Linus Torvalds
2004-02-21 14:16 ` Pavel Machek
2004-02-21 17:18 ` Linus Torvalds [this message]
2004-02-21 17:34 ` Pavel Machek
2004-02-21 17:44 ` Linus Torvalds
2004-02-21 18:36 ` Eric W. Biederman
2004-02-21 18:48 ` Pavel Machek
2004-02-21 19:03 ` Linus Torvalds
2004-02-21 19:30 ` Eric W. Biederman
2004-02-22 20:12 ` H. Peter Anvin
2004-02-22 20:32 ` Linus Torvalds
2004-02-22 20:33 ` H. Peter Anvin
2004-02-22 20:41 ` H. Peter Anvin
2004-02-19 0:12 Nakajima, Jun
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