Re: XDP socket rings, and LKMM litmus tests

On Thu, Mar 04, 2021 at 04:44:34PM +0100, maranget wrote:

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On 3 Mar 2021, at 21:22, Alan Stern [off-list ref] wrote:

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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