Re: MMIO and gcc re-ordering issue

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To: David Miller <davem@...>

Cc: <linux-arch@...>, <scottwood@...>, <linuxppc-dev@...>, <alan@...>, <linux-kernel@...>, <torvalds@...>, <tpiepho@...>

Subject: Re: MMIO and gcc re-ordering issue

Date: Monday, May 26, 2008 - 11:39 pm

On Mon, 2008-05-26 at 19:28 -0700, David Miller wrote:
quoted text> > 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.

Yes. As it is today, tg3 for example is potentially broken on all archs
with newer gcc unless we either add "memory" clobber to readl/writel or
stick some wmb's in there (just a random driver I picked).

So Linus, what is your take on that matter ?

Cheers,
Ben.


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Messages in current thread:

[PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Tue May 20, 4:40 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Andreas Schwab, (Tue May 20, 6:00 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Tue May 20, 6:11 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Andreas Schwab, (Tue May 20, 6:47 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Tue May 20, 7:14 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Andreas Schwab, (Wed May 21, 4:03 am)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Wed May 21, 4:25 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Benjamin Herrenschmidt, (Tue May 20, 5:16 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Tue May 20, 6:00 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Benjamin Herrenschmidt, (Wed May 21, 10:00 am)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Wed May 21, 3:44 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Benjamin Herrenschmidt, (Wed May 21, 4:41 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Scott Wood, (Tue May 20, 5:38 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Alan Cox, (Tue May 20, 6:15 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Scott Wood, (Tue May 20, 6:35 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Tue May 20, 6:55 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Benjamin Herrenschmidt, (Wed May 21, 10:01 am)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, David Miller, (Tue May 20, 6:39 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Scott Wood, (Tue May 20, 6:43 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, David Miller, (Tue May 20, 6:53 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Benjamin Herrenschmidt, (Fri May 23, 12:24 am)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Thu May 22, 6:56 pm)

MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Mon May 26, 9:33 pm)

Re: MMIO and gcc re-ordering issue, Jonathan Corbet, (Tue May 27, 11:28 am)

Re: MMIO and gcc re-ordering issue, David Miller, (Mon May 26, 9:40 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Mon May 26, 10:15 pm)

Re: MMIO and gcc re-ordering issue, David Miller, (Mon May 26, 10:28 pm)

Re: MMIO and gcc re-ordering issue, Alan Cox, (Tue May 27, 4:24 am)

Re: MMIO and gcc re-ordering issue, Arjan van de Ven, (Mon May 26, 11:42 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 3:08 am)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 11:50 am)

Re: MMIO and gcc re-ordering issue, Pavel Machek, (Sat May 31, 4:04 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 5:11 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 5:33 pm)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Thu May 29, 10:47 am)

Re: MMIO and gcc re-ordering issue, Jeremy Higdon, (Sat May 31, 3:52 am)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Mon Jun 2, 5:56 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 12:33 am)

Re: MMIO and gcc re-ordering issue, Jesse Barnes, (Tue Jun 3, 12:52 pm)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Thu Jun 5, 4:40 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Thu Jun 5, 4:43 am)

Re: MMIO and gcc re-ordering issue, Matthew Wilcox, (Thu Jun 12, 11:07 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Thu Jun 12, 8:07 pm)

Re: MMIO and gcc re-ordering issue, Jeremy Higdon, (Tue Jun 3, 4:15 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 4:19 am)

Re: MMIO and gcc re-ordering issue, Jeremy Higdon, (Tue Jun 3, 4:45 am)

Re: MMIO and gcc re-ordering issue, Jeremy Higdon, (Mon Jun 2, 5:02 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Thu May 29, 6:06 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Thu May 29, 6:25 pm)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Thu May 29, 11:56 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Thu May 29, 5:40 pm)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Fri May 30, 5:48 am)

Re: MMIO and gcc re-ordering issue, Pavel Machek, (Sat May 31, 4:14 am)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Mon Jun 2, 5:48 am)

Re: MMIO and gcc re-ordering issue, Jesse Barnes, (Thu May 29, 5:53 pm)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Fri May 30, 5:39 am)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Thu May 29, 5:48 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Thu May 29, 6:05 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Thu May 29, 9:53 pm)

Re: MMIO and gcc re-ordering issue, James Bottomley, (Thu May 29, 11:01 am)

Re: MMIO and gcc re-ordering issue, Jes Sorensen, (Fri May 30, 5:36 am)

Re: MMIO and gcc re-ordering issue, Jesse Barnes, (Fri May 30, 1:21 pm)

Re: MMIO and gcc re-ordering issue, Jeremy Higdon, (Sat May 31, 3:57 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 6:13 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 6:39 pm)

Re: MMIO and gcc re-ordering issue, James Bottomley, (Tue May 27, 12:37 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 1:38 pm)

Re: MMIO and gcc re-ordering issue, James Bottomley, (Tue May 27, 1:53 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 2:07 pm)

Re: MMIO and gcc re-ordering issue, Chris Friesen, (Tue May 27, 5:23 pm)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Tue May 27, 7:04 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 5:29 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue May 27, 2:17 pm)

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

Re: MMIO and gcc re-ordering issue, Arjan van de Ven, (Tue May 27, 12:20 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Mon May 26, 11:39 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 11:35 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 5:10 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 5:30 pm)

Re: MMIO and gcc re-ordering issue, Alan Cox, (Tue May 27, 5:38 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 5:59 pm)

Re: MMIO and gcc re-ordering issue, Matthew Wilcox, (Tue May 27, 5:53 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 6:02 pm)

Re: MMIO and gcc re-ordering issue, Alan Cox, (Tue May 27, 5:46 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 5:38 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 5:55 pm)

Re: MMIO and gcc re-ordering issue, Russell King, (Mon Jun 2, 3:24 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 12:16 am)

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

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue Jun 3, 6:26 pm)

Re: MMIO and gcc re-ordering issue, Matthew Wilcox, (Tue Jun 3, 5:33 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Tue Jun 3, 5:44 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 10:25 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Wed Jun 4, 2:39 am)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue Jun 3, 10:47 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 10:19 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Tue Jun 3, 2:47 pm)

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

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 10, 2:56 am)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Wed Jun 11, 1:20 am)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Wed Jun 11, 12:18 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Wed Jun 11, 1:00 am)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Wed Jun 11, 10:46 am)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Wed Jun 11, 1:13 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Wed Jun 11, 1:35 am)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Thu Jun 12, 8:14 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Thu Jun 12, 9:08 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Wed Jun 11, 2:02 am)

Re: MMIO and gcc re-ordering issue, Jesse Barnes, (Tue Jun 10, 1:41 pm)

Re: MMIO and gcc re-ordering issue, James Bottomley, (Tue Jun 10, 2:10 pm)

Re: MMIO and gcc re-ordering issue, Roland Dreier, (Tue Jun 10, 3:05 pm)

Re: MMIO and gcc re-ordering issue, Jesse Barnes, (Tue Jun 10, 3:19 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 10, 11:29 pm)

Re: MMIO and gcc re-ordering issue, Jesse Barnes, (Wed Jun 11, 12:07 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Thu Jun 12, 7:27 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue Jun 10, 11:40 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Wed Jun 11, 12:06 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 10:05 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue Jun 3, 10:46 pm)

Re: MMIO and gcc re-ordering issue, Alan Cox, (Wed Jun 4, 7:47 am)

Re: MMIO and gcc re-ordering issue, Matthew Wilcox, (Tue Jun 3, 2:55 pm)

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

Re: MMIO and gcc re-ordering issue, Matthew Wilcox, (Tue Jun 3, 5:35 pm)

Re: MMIO and gcc re-ordering issue, Trent Piepho, (Tue Jun 3, 5:58 pm)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 10:00 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue Jun 3, 12:32 am)

Re: MMIO and gcc re-ordering issue, Nick Piggin, (Tue Jun 3, 2:11 am)

Re: MMIO and gcc re-ordering issue, Paul Mackerras, (Tue Jun 3, 2:53 am)

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

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue Jun 3, 2:48 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 6:19 pm)

Re: MMIO and gcc re-ordering issue, Arnd Bergmann, (Thu May 29, 3:10 am)

Re: MMIO and gcc re-ordering issue, Alan Cox, (Thu May 29, 6:46 am)

Re: MMIO and gcc re-ordering issue, Matthew Wilcox, (Tue May 27, 5:42 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 6:17 pm)

Re: MMIO and gcc re-ordering issue, Haavard Skinnemoen, (Wed May 28, 4:36 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Thu May 29, 9:13 pm)

Re: MMIO and gcc re-ordering issue, Haavard Skinnemoen, (Fri May 30, 2:07 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Fri May 30, 3:24 am)

Re: MMIO and gcc re-ordering issue, Haavard Skinnemoen, (Fri May 30, 4:27 am)

Re: MMIO and gcc re-ordering issue, Geert Uytterhoeven, (Fri May 30, 5:22 am)

Re: MMIO and gcc re-ordering issue, Haavard Skinnemoen, (Mon Jun 2, 4:11 am)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Wed Jun 4, 11:31 am)

Re: MMIO and gcc re-ordering issue, Scott Wood, (Mon Jun 2, 11:48 am)

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

Re: MMIO and gcc re-ordering issue, Pantelis Antoniou, (Thu May 29, 7:05 am)

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

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

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 12:47 pm)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Tue May 27, 5:12 pm)

Re: MMIO and gcc re-ordering issue, Linus Torvalds, (Tue May 27, 1:31 pm)

Re: MMIO and gcc re-ordering issue, Ingo Molnar, (Mon Jun 2, 6:36 am)

Re: MMIO and gcc re-ordering issue, Benjamin Herrenschmidt, (Mon Jun 2, 5:53 pm)

MMIO and gcc re-ordering (Was: [PATCH] [POWERPC] Improve (in..., Benjamin Herrenschmidt, (Fri May 23, 8:36 am)

Re: MMIO and gcc re-ordering (Was: [PATCH] [POWERPC] Improve..., Benjamin Herrenschmidt, (Fri May 23, 8:50 am)

Re: MMIO and gcc re-ordering (Was: [PATCH] [POWERPC] Improve..., Scott Wood, (Fri May 23, 5:14 pm)

Re: MMIO and gcc re-ordering (Was: [PATCH] [POWERPC] Improve..., Benjamin Herrenschmidt, (Fri May 23, 6:47 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Benjamin Herrenschmidt, (Tue May 20, 6:02 pm)

Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code, Trent Piepho, (Tue May 20, 6:21 pm)

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