Re: MIPS-specific porting issue

Florian Lohoff <[email protected]> Mon, 6 Dec 2021 10:01:58 +0100

Newsgroups	gmane.linux.debian.ports.mips
Organization	rfc822 - pure communication
Message-ID	<[email protected]>

On Sat, Dec 04, 2021 at 12:07:29AM +0000, YANG Jiaxun wrote:
> Hi Stéphane.
> 
> MIPS do have a way to access count register from user space.
> Unfortunately there is no GCC intrinsic function for it, you may try following inline assembly.
> 
> static inline unsigned long get_count() {
>     unsigned long count;
>     asm volatile ("rdhwr %[rt], $2" : [rt] "=d" (count));
>     return count;
> }
> 
> return Val_long (get_count());

To be more precise - Not all CPUs have this (Older MIPS I for example
dont) but there is kernel emulation / instruction trapping for it.

And - I dont think Debian supports MIPS I targets anymore.

Flo
-- 
Florian Lohoff                                                     [email protected]
  Any sufficiently advanced technology is indistinguishable from magic.

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