linux-kernel - Re: PMTMR running too fast

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: <1165259962.6152.5.camel@localhost.localdomain>
Date:	Mon, 04 Dec 2006 11:19:22 -0800
From:	john stultz <johnstul@...ibm.com>
To:	Ian Campbell <ijc@...lion.org.uk>
Cc:	linux-kernel@...r.kernel.org, Andi Kleen <ak@...e.de>
Subject: Re: PMTMR running too fast

On Sun, 2006-12-03 at 13:50 +0000, Ian Campbell wrote:
> In older kernels arch/i386/kernel/timers/timer_pm.c:verify_pmtmr_rate
> contained a check for sensible PMTMR rate and disabled that clocksource
> if it was found to be out of spec[0]. This check seems to have been lost
> in the transition to drivers/clocksource/acpi_pm.c, the removal is in
> 61743fe445213b87fb55a389c8d073785323ca3e "Time: i386 Conversion - part
> 4: Remove Old timer_opts Code"[1] and the check is not present in the
> replacement 5d0cf410e94b1f1ff852c3f210d22cc6c5a27ffa "Time: i386
> Clocksource Drivers"[2].

Fedora has a bug covering this:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=211902


> Is there a specific reason the check was removed (I couldn't see on in
> the archives) or was it simply overlooked? Without it I need to pass
> clocksource=tsc to have 2.6.18 work correctly on an older K6 system with
> an Aladdin chipset (will dig out the precise details if required). Would
> a patch to reintroduce the check be acceptable or would some sort of
> blacklist based solution be more acceptable?

If I recall correctly, it was pulled because there was some question as
to if it was actually needed (x86_64 didn't need it) and it slows down
the boot time (although not by much). 

I'm fine just re-adding it. Although if the number of affected systems
are small we could just blacklist it (Ian, mind sending dmidecode
output?).

Andi, your thoughts?

thanks
-john


-
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/