linux-kernel - Re: [PATCH 7/8] cpufreq: Add support for x86 cpuinfo auto loading v3

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: <20111221213009.GA2568@redhat.com>
Date:	Wed, 21 Dec 2011 16:30:10 -0500
From:	Dave Jones <davej@...hat.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Andi Kleen <ak@...ux.intel.com>, Thomas Renninger <trenn@...e.de>,
	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org,
	kay.sievers@....org, kay.sievers@...y.org
Subject: Re: [PATCH 7/8] cpufreq: Add support for x86 cpuinfo auto loading v3

On Wed, Dec 21, 2011 at 12:14:57PM -0800, H. Peter Anvin wrote:
 > On 12/21/2011 12:12 PM, Andi Kleen wrote:
 > >>> +static const struct x86_cpu_id powernow_k8_ids[] = {
 > >>> +	{ X86_VENDOR_AMD, 0xf, },
 > >>> +	{ X86_VENDOR_AMD, 0x10, },
 > >>> +	{ X86_VENDOR_AMD, 0x11, },
 > >>> +	{ X86_VENDOR_AMD, 0x12, },
 > >>> +	{ X86_VENDOR_AMD, 0x13, },
 > >>> +	{ X86_VENDOR_AMD, 0x14, },
 > >> { X86_VENDOR_AMD, 0x15, },
 > >>
 > >> Should also have BullDozer family included.
 > > 
 > > I think it really needs a cpuid feature bit for the hwpstate.  This is
 > > not in one of the normal CPUID leaves, so the amd specific CPU init
 > > code would need to set it.
 > > 
 > > I added 0x15 for now, but it would be good if someone with the hardware
 > > fixed it like this.
 > > 
 > > Then could just add a match on "AMD-hw pstate" or so.
 > > 
 > 
 > Agreed.  This is literally screaming for a synthetic CPUID bit.

A synthetic one is pointless, because you'd just be duplicating something
similar to the above in generic code that would need updating for every new stepping.

If anything other than powernow-k8 cared, there might be a more
compelling argument, but I don't see the point in moving something that
only this driver cares about to common code.

	Dave

--
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/