Re: MMIO and gcc re-ordering issue

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From: David Miller

Subject: Re: MMIO and gcc re-ordering issue

Date: Monday, May 26, 2008 - 7:28 pm

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 27 May 2008 12:15:40 +1000

quoted text> Some of them. USB comes to mind. I'd be happy to make it "the rule" and
> document that MMIO vs. coherent access aren't implicitely ordered. I
> would still keep them ordered on powerpc for a little while tho until
> I'm happy enough with driver auditing.
> 
> But heh, it's you who was telling me that it would be a bad engineering
> decision and we had to make everybody look like x86 & fully ordered :-)
> I decided to agree back then and stuck all those nasty heavy barriers
> in the powerpc variants of readl/writel/...

I still believe this.

It's just another complicated thing for driver authors to get wrong.
The other side of the coin is of course the cost.

The only thing I am absolutely sure of is that we should make a
decision fast, document it, and just stick to it.
--
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Messages in current thread:

[PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Tue May 20, 1:40 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Benjamin Herrenschmidt, (Tue May 20, 2:16 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Scott Wood, (Tue May 20, 2:38 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Tue May 20, 3:00 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Andreas Schwab, (Tue May 20, 3:00 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Benjamin Herrenschmidt, (Tue May 20, 3:02 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Tue May 20, 3:11 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Alan Cox, (Tue May 20, 3:15 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Tue May 20, 3:21 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Scott Wood, (Tue May 20, 3:35 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, David Miller, (Tue May 20, 3:39 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Scott Wood, (Tue May 20, 3:43 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Andreas Schwab, (Tue May 20, 3:47 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, David Miller, (Tue May 20, 3:53 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Tue May 20, 3:55 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Tue May 20, 4:14 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Andreas Schwab, (Wed May 21, 1:03 am)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Benjamin Herrenschmidt, (Wed May 21, 7:00 am)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Benjamin Herrenschmidt, (Wed May 21, 7:01 am)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Wed May 21, 12:44 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Wed May 21, 1:25 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Benjamin Herrenschmidt, (Wed May 21, 1:41 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Thu May 22, 3:56 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Benjamin Herrenschmidt, (Thu May 22, 9:24 pm)

MMIO and gcc re-ordering (Was: [PATCH] [POWERPC] Improve ( ..., Benjamin Herrenschmidt, (Fri May 23, 5:36 am)

Re: MMIO and gcc re-ordering (Was: [PATCH] [POWERPC] Impro ..., Benjamin Herrenschmidt, (Fri May 23, 5:50 am)

Re: MMIO and gcc re-ordering (Was: [PATCH] [POWERPC] Impro ..., Scott Wood, (Fri May 23, 2:14 pm)

Re: MMIO and gcc re-ordering (Was: [PATCH] [POWERPC] Impro ..., Benjamin Herrenschmidt, (Fri May 23, 3:47 pm)

MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Mon May 26, 6:33 pm)

Re: MMIO and gcc re-ordering issue, David Miller, (Mon May 26, 6:40 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Mon May 26, 7:15 pm)

Re: MMIO and gcc re-ordering issue, David Miller, (Mon May 26, 7:28 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Mon May 26, 8:39 pm)

Re: MMIO and gcc re-ordering issue, Arjan van de Ven, (Mon May 26, 8:42 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Mon May 26, 9:08 pm)

Re: MMIO and gcc re-ordering issue, Arjan van de Ven, (Mon May 26, 9:20 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 12:08 am)

Re: MMIO and gcc re-ordering issue, Alan Cox, (Tue May 27, 1:24 am)

Re: MMIO and gcc re-ordering issue, Jonathan Corbet, (Tue May 27, 8:28 am)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 8:35 am)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 8:50 am)

Re: MMIO and gcc re-ordering issue, James Bottomley, (Tue May 27, 9:37 am)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 9:47 am)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 10:31 am)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 10:38 am)

Re: MMIO and gcc re-ordering issue, James Bottomley, (Tue May 27, 10:53 am)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 11:07 am)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 11:17 am)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Tue May 27, 11:23 am)

Re: MMIO and gcc re-ordering issue, Scott Wood, (Tue May 27, 11:33 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 2:10 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 2:11 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 2:12 pm)

Re: MMIO and gcc re-ordering issue, Chris Friesen, (Tue May 27, 2:23 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 2:29 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 2:30 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 2:33 pm)

Re: MMIO and gcc re-ordering issue, Alan Cox, (Tue May 27, 2:38 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 2:38 pm)

Re: MMIO and gcc re-ordering issue, Matthew Wilcox, (Tue May 27, 2:42 pm)

Re: MMIO and gcc re-ordering issue, Alan Cox, (Tue May 27, 2:46 pm)

Re: MMIO and gcc re-ordering issue, Matthew Wilcox, (Tue May 27, 2:53 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 2:55 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 2:59 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 3:02 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 3:13 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 3:17 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 3:19 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 3:39 pm)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Tue May 27, 4:04 pm)

Re: MMIO and gcc re-ordering issue, Haavard Skinnemoen, (Wed May 28, 1:36 am)

Re: MMIO and gcc re-ordering issue, Arnd Bergmann, (Thu May 29, 12:10 am)

Re: MMIO and gcc re-ordering issue, Alan Cox, (Thu May 29, 3:46 am)

Re: MMIO and gcc re-ordering issue, Pantelis Antoniou, (Thu May 29, 4:05 am)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Thu May 29, 7:47 am)

Re: MMIO and gcc re-ordering issue, James Bottomley, (Thu May 29, 8:01 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Thu May 29, 2:40 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Thu May 29, 2:48 pm)

Re: MMIO and gcc re-ordering issue, Jesse Barnes, (Thu May 29, 2:53 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Thu May 29, 3:05 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Thu May 29, 3:06 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Thu May 29, 3:25 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Thu May 29, 6:13 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Thu May 29, 6:53 pm)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Thu May 29, 8:56 pm)

Re: MMIO and gcc re-ordering issue, Haavard Skinnemoen, (Thu May 29, 11:07 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Fri May 30, 12:24 am)

Re: MMIO and gcc re-ordering issue, Haavard Skinnemoen, (Fri May 30, 1:27 am)

Re: MMIO and gcc re-ordering issue, Geert Uytterhoeven, (Fri May 30, 2:22 am)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Fri May 30, 2:36 am)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Fri May 30, 2:39 am)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Fri May 30, 2:48 am)

Re: MMIO and gcc re-ordering issue, Jesse Barnes, (Fri May 30, 10:21 am)

Re: MMIO and gcc re-ordering issue, Jeremy Higdon, (Sat May 31, 12:52 am)

Re: MMIO and gcc re-ordering issue, Jeremy Higdon, (Sat May 31, 12:57 am)

Re: MMIO and gcc re-ordering issue, Pavel Machek, (Sat May 31, 1:04 am)

Re: MMIO and gcc re-ordering issue, Pavel Machek, (Sat May 31, 1:14 am)

Re: MMIO and gcc re-ordering issue, Russell King, (Mon Jun 2, 12:24 am)

Re: MMIO and gcc re-ordering issue, Haavard Skinnemoen, (Mon Jun 2, 1:11 am)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Mon Jun 2, 2:48 am)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Mon Jun 2, 2:56 am)

Re: MMIO and gcc re-ordering issue, Ingo Molnar, (Mon Jun 2, 3:36 am)

Re: MMIO and gcc re-ordering issue, Scott Wood, (Mon Jun 2, 8:48 am)

Re: MMIO and gcc re-ordering issue, Jeremy Higdon, (Mon Jun 2, 2:02 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Mon Jun 2, 2:53 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Mon Jun 2, 9:16 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Mon Jun 2, 9:32 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Mon Jun 2, 9:33 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Mon Jun 2, 11:11 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Mon Jun 2, 11:48 pm)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Mon Jun 2, 11:53 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 12:18 am)

Re: MMIO and gcc re-ordering issue, Haavard Skinnemoen, (Tue Jun 3, 12:46 am)

Re: MMIO and gcc re-ordering issue, Jeremy Higdon, (Tue Jun 3, 1:15 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 1:19 am)

Re: MMIO and gcc re-ordering issue, Jeremy Higdon, (Tue Jun 3, 1:45 am)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue Jun 3, 7:47 am)

Re: MMIO and gcc re-ordering issue, Jesse Barnes, (Tue Jun 3, 9:52 am)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Tue Jun 3, 11:47 am)

Re: MMIO and gcc re-ordering issue, Matthew Wilcox, (Tue Jun 3, 11:55 am)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue Jun 3, 12:07 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Tue Jun 3, 12:43 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Tue Jun 3, 12:57 pm)

Re: MMIO and gcc re-ordering issue, Matthew Wilcox, (Tue Jun 3, 2:33 pm)

Re: MMIO and gcc re-ordering issue, Matthew Wilcox, (Tue Jun 3, 2:35 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Tue Jun 3, 2:44 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Tue Jun 3, 2:58 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue Jun 3, 3:26 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 7:00 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 7:05 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 7:19 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 7:25 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue Jun 3, 7:46 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Tue Jun 3, 11:39 pm)

Re: MMIO and gcc re-ordering issue, Alan Cox, (Wed Jun 4, 4:47 am)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Wed Jun 4, 8:31 am)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Thu Jun 5, 1:40 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Thu Jun 5, 1:43 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Mon Jun 9, 11:56 pm)

Re: MMIO and gcc re-ordering issue, Jesse Barnes, (Tue Jun 10, 10:41 am)

Re: MMIO and gcc re-ordering issue, James Bottomley, (Tue Jun 10, 11:10 am)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue Jun 10, 12:05 pm)

Re: MMIO and gcc re-ordering issue, Jesse Barnes, (Tue Jun 10, 12:19 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 10, 8:29 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue Jun 10, 8:40 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 10, 9:06 pm)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Tue Jun 10, 9:18 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 10, 10:00 pm)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Tue Jun 10, 10:13 pm)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Tue Jun 10, 10:20 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 10, 10:35 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 10, 11:02 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Wed Jun 11, 7:46 am)

Re: MMIO and gcc re-ordering issue, Jesse Barnes, (Wed Jun 11, 9:07 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Thu Jun 12, 4:27 am)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Thu Jun 12, 5:14 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Thu Jun 12, 6:08 am)

Re: MMIO and gcc re-ordering issue, Matthew Wilcox, (Thu Jun 12, 8:07 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Thu Jun 12, 5:07 pm)

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