Messages in this thread | | | Date | Mon, 29 May 2006 15:17:40 -0400 (EDT) | From | Nicolas Pitre <> | Subject | Re: [PATCHSET] block: fix PIO cache coherency bug |
| |
On Thu, 2 Mar 2006, Jens Axboe wrote:
> On Thu, Mar 02 2006, Russell King wrote: > > On Thu, Mar 02, 2006 at 12:46:28PM -0600, James Bottomley wrote: > > > On Wed, 2006-02-22 at 17:27 +0900, Tejun Heo wrote: > > > > The objection raised by James Bottomley is that although syncing the > > > > kernel page is the responsbility of the driver, syncing user page is > > > > not; thus, use of flush_dcache_page() is excessive. James suggested > > > > use of flush_kernel_dcache_page(). > > > > > > The problem is that it's not only excessive, it would entangle us with > > > mm locking. Basically, all you want to ensure is that the underlying > > > memory has the information after you've done (rather than the CPU > > > cache), flush_kernel_dcache_page() will achieve this. The block layer > > > itself takes care of user space coherency. > > > > Your understanding of the problem on ARM remains fundamentally flawed. > > I see no way to resolve this since you don't seem to listen or accept > > my reasoning. > > > > Therefore, message I'm getting from you is that we are not allowed to > > have an ARM system which can possibly work correctly with PIO. > > > > As a result, I have no further interest in trying to resolve this issue, > > period. ARM people will just have to accept that PIO mode IDE drivers > > just will not be an option. > > Hey Russell calm down, lets get this thing fixed in the easiest and > least intrusive way for 2.6.17. As mentioned before, this isn't actually > a new problem by any stretch, a 2.6.17 solution would be acceptable to > you I hope.
Has any discussion about this problem lead to some consensus?
> What do you think of the kmap_atomic_pio() (notoriously bad at names, > but it should get the point across) and kunmap_atomic_pio(), the latter > accepting a read/write flag to note if we wrote to a vm page? > > This is basically Tejuns original patch set, just moving it out of the > block layer so it's a generel exported property of the kmap api.
What was the problem with Tejun's patchset already to which RMK (and many others) agreed?
I do have hardware that exhibits the problem and therefore I wish the discussion could be resumed.
Nicolas - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |