Messages in this thread | | | Date | Fri, 19 Sep 2008 14:46:23 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: [PATCH] x86: x86_{phys,virt}_bits field also for i386 (v3) |
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Jan Beulich wrote: >> I would say the simplest thing to do here is be explicit: >> >> if (sizeof(addr) == sizeof(u64)) >> return !(addr >> boot_cpu_data.x86_phys_bits); >> else >> return 1; >> >> That's not ideal, but I guess its good enough. I assume x86_phys_bits >> can never be less than 32? >> > > Yes, one could do it that way. But what's the point of having RESOURCES_64BIT > set and resource_size_t nevertheless being a 32-bit quantity?
CONFIG_RESOURCES_64BIT was removed, so testing for it makes no sense. (Not being able to distinguish between non-existent and unset config variables is an outstanding Kconfig problem.)
Directly testing the size of the type is the most robust approach, though it would be simpler if shifting a variable by more bits than its size had a guaranteed 0 result.
> And why, > independent of that, was ioremap() not changed to use phys_addr_t?
Well, ioremap is supposed to be used for IO mappings, so taking a resource_size_t still makes sense.
The question of whether resource_size_t should be the same as a phys_addr_t is still a bit undecided. Andrew's of the opinion that they should be separate, and that it could make sense to have 32-bit resource addresses in an otherwise 64-bit system. I think that's a pretty narrow special case (32-bit PAE system with no 64-bit IO devices), and its not worth having the extra definition complexity for it.
J
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