Re: [Pnet-developers] [patch #3119] jit_flush_exec () for x86

[Rhys Weatherley]

On Tuesday 08 June 2004 10:06 pm, Miroslaw Dobrzanski-Neumann wrote:

> "The Pthreads standard requires library implementors to synchronize memory
> writes (with respect to reads and other writes) for a subset of Pthreads
> and POSIX.1 functions.

I think this only applies to reads/writes on the contents of the data cache on 
the chip.  Some CPU's have separate instructions for flushing the data cache 
and the instruction cache (e.g. ppc).

The purpose of "jit_flush_exec" is to flush information out of the data cache, 
invalidate the corresponding lines in the instruction cache (in case there 
was something there already), and then force the CPU to reload the 
instruction cache from what was just ejected from the data cache.

I had a quick look at the LinuxThreads code for ppc, and its memory flush 
macro looks nothing like "jit_flush_exec".  It's only affects the data cache 
from what I can tell.

We are stuck with ugly assembly hacks for the duration, unfortunately.

Cheers,

Rhys.