Messages in this thread | | | Date | Fri, 27 Feb 2009 07:57:17 +0100 | From | Ingo Molnar <> | Subject | Re: [patch] x86: optimize __pa() to be linear again on 64-bit x86 |
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* Tejun Heo <tj@kernel.org> wrote:
> Hello, > > Ingo Molnar wrote: > > Yeah, we can do this complete conversion. > > > > I'll clean it up some more. I think the best representation of > > this will be via a virt_to_sym() and sym_to_virt() space. That > > makes it really clear when we are moving from the symbol space > > to the linear space and back. > > For arch code, maybe it's maintainable but with my driver developer > hat on I gotta say virt_to_page() not working on .data/.bss is quite > scary. [...]
Well, we have a debug mechanism in place.
As i suggested it in my first mail we can run with debug enabled for a cycle and then turn on the optimization by default (with the debug option still available too).
Drivers doing DMA on .data/.bss items is rather questionable anyway (and dangerous as well, on any platform where there's coherency problems if DMA is misaligned, etc.), and a quick look shows there's at most 2-3 dozen examples of that in all of drivers/*.
Ingo
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