> Could anybody tell me the difference between these two symbols ?
>
> I know that one is a macro and the other one is an inline function,
> so the latter performs type checkings but I don't see anything else.
>
> thanks
>
> Francis
>
Here is the answer (by Dave Hansen, 2004):
__pa() is simply supposed to be the addr-PAGE_OFFSET calculation.
virt_to_phys() will be guaranteed to take care of any layout changes if
kernel addresses ever fail to be mapped flat, and 1:1 with the physical
address layout.
So, let's say that someone is working on ... say ... memory hotplug.
They will be modifying the virt_to_phys() function to make up for any
weird mappings that are going on. But, they'll leave __{v,p}a alone,
because those are used for stuff that occurs very early, even at compile
time.
More virt_to_phys() and less __pa() will save me lots of auditing later
on :) If you're not in early boot, or really know what you're doing,
use virt_to_phys() and cousins.
Plus, it's more type safe.
Lukas Jelinek
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
