Messages in this thread | | | Subject | Re: pci-sysfs resource mmap broken | From | Benjamin Herrenschmidt <> | Date | Wed, 27 Apr 2005 14:30:21 +1000 |
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On Tue, 2005-04-26 at 21:55 -0600, Grant Grundler wrote: > On Wed, Apr 27, 2005 at 08:47:34AM +1000, Benjamin Herrenschmidt wrote: > > No. I don't agree. userspace has no business understanding the kernel > > resources content. > > Sorry - you are right. Userspace doesn't need to understand kernel > resources. It just needs some sort of handle so it can talk > to the device in whatever way is appropriate. I was thinking > the resource content (which happens to be CPU View of a BAR) > could be that handle.
Ok, we are crossing each other here, I was about to reply that you were indeed right :) Anyway, I'm about to post another message explaining all that I think I found and my proposed fix for ppc. Should be up as soon as I have finished testing the patch.
> ... > > The only thing I dislike a bit is that forces me to read the BAR on > > every access to "un-offset" the kernel resource. We may be able to have > > some arch hook do that properly, but for now, that would fix the problem > > and make the whole stuff work again. > > > What is wrong with reading the BAR? > Is the "IO View" needed in the performance path someplace? > > It should be trivial since config space is exported via /sys and /proc. > libpci probably already has everything that's needed.
True, but then, I tend to prefer you idea of a CPU view ... so my new "proposal" is something like pci_resource_to_user() implementation. Anyway, wait a bit so I can polish this patch and tell me what you think :)
Ben.
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