Re: XDP socket rings, and LKMM litmus tests

[Paul E. McKenney]

On Thu, Mar 04, 2021 at 04:44:34PM +0100, maranget wrote:
> 
> 
> > On 3 Mar 2021, at 21:22, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> > 
> >>> 
> >>> Local variables absolutely should be treated just like CPU registers, if 
> >>> possible.  In fact, the compiler has the option of keeping local 
> >>> variables stored in registers.
> >>> 
> >>> (Of course, things may get complicated if anyone writes a litmus test 
> >>> that uses a pointer to a local variable,  Especially if the pointer 
> >>> could hold the address of a local variable in one execution and a 
> >>> shared variable in another!  Or if the pointer is itself a shared 
> >>> variable and is dereferenced in another thread!)
> >> 
> >> Good point!  I did miss this complication.  ;-)
> > 
> > I suspect it wouldn't be so bad if herd7 disallowed taking addresses of 
> > local variables.
> 
> Herd7 does disallow taking addresses of local variables.

Good to know, and thank you!

> However, such  tests can still be run on machine, provided function bodies are accepted by the C compiler.

True, but that would be outside of the LKMM proper, correct?

							Thanx, Paul