Re: cpu features testing 32 vs 64 bit
From: David Gibson <hidden>
Date: 2005-09-09 00:08:57
On Fri, Sep 09, 2005 at 12:36:39AM +0200, Arnd Bergmann wrote:
On Freedag 09 September 2005 00:02, Kumar Gala wrote:quoted
On Sep 8, 2005, at 4:48 PM, Dan Malek wrote:quoted
If we #define CPU_FTR_xxx as a 0 or all 1's for processors that have or don't have these features, will the compiler be smart enough to recognize an always true or false condition and remove the test (or code as appropriate)?The compiler is smart enough in this case since cpu_has_feature() is an inline function.I actually wrote a patch that solves the problem in a very generic way, see http://patchwork.ozlabs.org/linuxppc/patch?id=1048 . I don't remember exactly if there were serious objections against the patch at that time, but it looks like a much cleaner solution to me than defining CPU_FTR_xxx to different values depending on the configuration.
And we already use a mechanism essentially identical to Arnd's for fw_has_feature(). -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/people/dgibson