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: <B28277FD4E0F9247A3D55704C440A140D5ADEC78@pgsmsx504.gar.corp.intel.com>
Date:	Thu, 6 Aug 2009 07:10:00 +0800
From:	"Tan, Wei Chong" <wei.chong.tan@...el.com>
To:	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	John Stultz <johnstul@...ibm.com>
CC:	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>
Subject: RE: [GIT PULL] Additional x86 fixes for 2.6.31-rc5

> Sure, we might want the error term to be even smaller, but 
> in no way does it actually invalidate any of the logic - 
> the 'tsc' reading is just a guess anyway. Also, I think 
> that the real issue isn't even an SMI - but the fact that 
> in the very last iteration of the loop, there's no 
> serializing instruction _after_ the last 'rdtsc'. So even 
> in the absense of SMI's, we do have a situation where the 
> cycle counter was read without proper serialization.
> 

Hi,

I just recall something which I cannot understand.  Earlier when we observed the wrong CPU frequency phenomenon (1666MHz being identified as 1800MHz), we use the same CPU and put them on 2 different boards.  On one board, the failure rate is high (about 1 out of every 20).  On the other, it almost never fails.
We compare the 2 boards and they are quite close to each other with one very prominent difference.  The failing board has no PS/2 port and so is using all USB keyboard/mouse while the good board uses PS/2 keyboard/mouse.
Thus, we plug in a USB keyboard on the good board and were then able produce the failure on the good board (despite at a lower failure rate, 1 out of every 100).
Does this not point to SMI?

Regards,
Wei Chong.
--
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/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ