Messages in this thread | | | Subject | Re: MMIO and gcc re-ordering (Was: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code) | From | Benjamin Herrenschmidt <> | Date | Fri, 23 May 2008 08:50:16 -0400 |
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On Fri, 2008-05-23 at 08:36 -0400, Benjamin Herrenschmidt wrote: > > - mandate some kind of dma_sync_for_device/cpu on consistent memory. > Almost no driver do that currently tho. They only do that for non > consistent memory mapped with dma_map_*. > > - mandate the use of wmb,rmb,mb barriers for use between memory > accesses and MMIOs for ordering them. (ie. fix drivers that don't do > it). Advantage for powerpc is that I can remove (after some auditing of > course) the added heavy barriers in the MMIO accessors themselves.
Note that the above is my preferred approach, and a lot of drivers happen to already do this.
> - stick a full memory clobber in all MMIO (and PIO) accessors on all > archs. > > Any other idea ? preference ?
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