Re: [PATCH] qemu/timer: Don't use RDTSC on i486

[Petr Cvek]

Actually I was thinking about mentioning it in the commit message also, but I 
wasn't able
to find any specification for that (if all compilers use it).

Other problem is the __tune_i386__ is also set when -mtune=i386 (but with 
-march=i686).

But if the general idea of changing the code for 486 is OK it can be added also.

Petr

Dne 26. 11. 23 v 13:37 Samuel Tardieu napsal(a):
> 
> Petr Cvek <petrcvekcz@gmail.com> writes:
> 
>> GCC defines __i386__ for i386 and i486, which both lack RDTSC instruction.
>> The i386 seems to be impossible to distinguish, but i486 can be identified
>> by checking for undefined __i486__.
> 
> Couldn't you check for an undefined __tune_i386__, which would be set by both 
> GCC and LLVM when using -march=i386.
> 
>  Sam