Re: gnu asm help...

[Timur Tabi <ttabi@interactivesi.com>]

** Reply to message from "Petr Vandrovec" <VANDROVE@vc.cvut.cz> on Tue, 19 Jun
2001 01:36:26 MET-1


> No. Another CPU might increment value between LOCK INCL and
> fetching v->counter. On ia32 architecture you are almost out of
> luck. You can either try building atomic_inc around CMPXCHG,
> using it as conditional store (but CMPXCHG is not available 
> on i386), or you can just guard your atomic variable with 
> spinlock - but in that case there is no reason for using atomic_t 
> at all.

Oh, I see the problem.  You could do something like this:

cli
mov %0, %%eax
inc %%eax
mov %%eax, %0
sti

and then return eax, but that won't work on SMP (whereas the "lock inc" does).
Doing a global cli might work, though.


-- 
Timur Tabi - ttabi@interactivesi.com
Interactive Silicon - http://www.interactivesi.com