From: Alain Knaff <alain@knaff.lu>
To: Andi Kleen <andi@firstfloor.org>
Cc: Arjan van de Ven <arjan@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Mark Hounschell <markh@compro.net>,
"Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
"dmarkh@cfl.rr.com" <dmarkh@cfl.rr.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"fdutils@fdutils.linux.lu" <fdutils@fdutils.linux.lu>,
"Li, Shaohua" <shaohua.li@intel.com>, Ingo Molnar <mingo@elte.hu>,
morgan@physics.ucla.edu, JONES@UINPLA.NPL.UIUC.EDU
Subject: Re: [Fdutils] DMA cache consistency bug introduced in 2.6.28
Date: Sun, 27 Dec 2009 13:28:37 +0100 [thread overview]
Message-ID: <4B3752F5.3080205@knaff.lu> (raw)
In-Reply-To: <20091226164029.GA10256@basil.fritz.box>
Andi Kleen wrote:
>>> Does pmqos work with apci=off etc.?
>> yes
>>
>>> I didn't think it shut down
>>> the classic "HLT" idle, does it?
>> it does if you specify a latency of 0; it will then go into the
>> spin-only state until you give up your latency requirement
>
> I looked at it this evening, but it seems like pm_qos is not
> interrupt safe (e.g. calls blocking notifiers) and floppy currently does
> enable/disable_hlt from interrupts and bottom halves.
>
> Would need some more infrastructure work or restructuring
> of the floppy driver.
>
> -Andi
disable_hlt/enable_hlt was only needed to work around a bug on TM4000
(Texas Instrument) Laptops which were popular around 1994 / 1995.
Basically, as soon as the CPU went into hlt() state, so did the DMA
controller, either causing a really slow transfer, or (worse) a buffer
over/underrun which failed the operation.
On hardware unaffected by this particular bug (which would be most
hardware around now, 14 years after the fact...), these calls can safely
be removed.
Regards,
Alain
next prev parent reply other threads:[~2009-12-27 12:30 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
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2009-12-17 17:00 ` DMA cache consistency bug introduced in 2.6.28 (Was: Re: [Fdutils] Cannot format floppies under kernel 2.6.*?) Alain Knaff
2009-12-17 17:27 ` Linus Torvalds
2009-12-17 18:21 ` DMA cache consistency bug introduced in 2.6.28 Krzysztof Halasa
2009-12-17 20:46 ` DMA cache consistency bug introduced in 2.6.28 (Was: Re: [Fdutils] Cannot format floppies under kernel 2.6.*?) Alain Knaff
2009-12-17 21:14 ` Linus Torvalds
2009-12-17 22:11 ` Alain Knaff
2009-12-17 22:43 ` Linus Torvalds
2009-12-17 23:24 ` Alain Knaff
2009-12-18 8:59 ` Mark Hounschell
2009-12-18 10:55 ` [Fdutils] DMA cache consistency bug introduced in 2.6.28 (Was: " Mark Hounschell
2009-12-18 15:01 ` [Fdutils] DMA cache consistency bug introduced in 2.6.28 Krzysztof Halasa
2009-12-18 15:22 ` [Fdutils] DMA cache consistency bug introduced in 2.6.28 (Was: Re: Cannot format floppies under kernel 2.6.*?) Linus Torvalds
2009-12-18 15:28 ` Mark Hounschell
2009-12-18 15:45 ` Linus Torvalds
2009-12-18 20:04 ` Mark Hounschell
2009-12-18 20:15 ` Linus Torvalds
2009-12-22 15:11 ` Mark Hounschell
2009-12-22 17:38 ` Linus Torvalds
2009-12-22 17:57 ` Mark Hounschell
2009-12-22 23:37 ` Pallipadi, Venkatesh
2009-12-23 0:22 ` Mark Hounschell
2009-12-23 13:02 ` Mark Hounschell
2009-12-23 15:10 ` Pallipadi, Venkatesh
2009-12-23 15:34 ` Mark Hounschell
2009-12-23 15:57 ` Mark Hounschell
2009-12-23 16:31 ` Linus Torvalds
2009-12-23 16:38 ` [Fdutils] DMA cache consistency bug introduced in 2.6.28 Andi Kleen
2009-12-23 16:49 ` Linus Torvalds
2009-12-23 17:08 ` Andi Kleen
2009-12-25 12:21 ` Arjan van de Ven
2009-12-25 20:33 ` Andi Kleen
2009-12-26 9:38 ` Arjan van de Ven
2009-12-26 16:40 ` Andi Kleen
2009-12-27 12:28 ` Alain Knaff [this message]
2009-12-28 1:54 ` Andi Kleen
2009-12-28 10:27 ` Alain Knaff
2009-12-28 14:54 ` Andi Kleen
2009-12-27 11:09 ` Pavel Machek
2009-12-28 20:54 ` Mark Hounschell
2009-12-23 17:19 ` Pallipadi, Venkatesh
2009-12-23 17:16 ` Andi Kleen
2009-12-23 20:11 ` alain
2009-12-23 17:41 ` Mark Hounschell
2009-12-23 18:01 ` Linus Torvalds
2009-12-23 18:11 ` Mark Hounschell
2009-12-23 19:18 ` Pallipadi, Venkatesh
2009-12-23 19:35 ` Mark Hounschell
2009-12-23 20:30 ` Pallipadi, Venkatesh
2009-12-23 20:34 ` alain
2009-12-23 21:34 ` Pallipadi, Venkatesh
2010-01-08 17:42 ` Mark Hounschell
2010-01-12 0:19 ` Pallipadi, Venkatesh
2010-01-12 9:04 ` Mark Hounschell
2010-01-15 2:01 ` Pallipadi, Venkatesh
2010-01-15 9:39 ` Mark Hounschell
2010-01-15 18:02 ` Mark Hounschell
2010-01-21 19:09 ` [PATCH] x86: Disable HPET MSI on ATI SB700/SB800 Pallipadi, Venkatesh
2010-01-22 22:00 ` [tip:x86/urgent] " tip-bot for Pallipadi, Venkatesh
2010-01-23 6:51 ` tip-bot for Pallipadi, Venkatesh
2010-01-23 7:21 ` [PATCH] " Yuhong Bao
2010-01-25 17:10 ` Andreas Herrmann
2010-01-28 9:17 ` Mark Hounschell
2010-01-28 13:25 ` Mark Hounschell
2010-01-28 13:41 ` Borislav Petkov
2010-01-28 14:45 ` Mark Hounschell
2010-05-17 14:59 ` Andreas Herrmann
2010-05-17 15:10 ` Yuhong Bao
2010-05-17 15:12 ` Linus Torvalds
2010-05-17 16:46 ` Andreas Herrmann
2010-05-18 0:56 ` Robert Hancock
2010-05-18 1:02 ` Linus Torvalds
2010-05-18 1:06 ` Robert Hancock
2010-05-18 8:45 ` Andi Kleen
2010-05-18 23:22 ` Robert Hancock
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