This is the mail archive of the libc-alpha@sourceware.org mailing list for the glibc project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH] powerpc: New feature - HWCAP/HWCAP2 bits in the TCB


On Fri, Jul 03, 2015 at 09:53:13PM +0200, OndÅej BÃlka wrote:
> hwcap.h:
> int __hwcap __attribute__ ((visibility ("hidden"))) ;
> 
> hwcap.c:
> 
> #include <hwcap.h>
> 
> // gcc needs to make this first constructor.
> extern int __global_hwcap;
> void __attribute__ ((constructor)) 
> set_hwcap () 
> {
>   __hwcap = __global_hwcap;
> }

We considered using this scheme.  In fact, I put forward the idea.
However, it was discarded as second best, due to the need to set up
GOT/TOC addressing on a variable access.  Nothing beats Steve's single
instruction "ld r,-0x7068(r13)" to read hwcap.

-- 
Alan Modra
Australia Development Lab, IBM


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]