linux-kernel - Re: P6 NOPs again: MPSC?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <47D62A0D.3070107@zytor.com>
Date:	Tue, 11 Mar 2008 07:43:25 +0100
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Hugh Dickins <hugh@...itas.com>
CC:	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: P6 NOPs again: MPSC?

Hugh Dickins wrote:
> 
> Yup, I realized that (with || in place of &&): I meant that perhaps
> it was supposed to say X86_64 || (!X86_GENERIC && (M686 || ....))
> since quite a lot of other options there have "|| X86_64" to cover
> all the 64-bit possibilities at once i.e. is it only MPSC that
> needs to be added, or both MPSC and CPU_GENERIC?
> 

No.  The left-hand clause (X86_64 || !X86_GENERIC) indicates when using 
these NOPs are *permitted*; the right-hand clause indicates when doing 
so is *desirable*.  The latter isn't, for example, for K8, even on 64 bits.

	-hpa

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/