Messages in this thread | | | Date | Thu, 7 Aug 2008 18:07:02 +0200 | From | Andi Kleen <> | Subject | Re: [ANNOUNCE] Merkey's Kernel Debugger |
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> Also, whoever wrote "/Documentation/volatiles_are_evil" must not have > worked with the busted-ass GNU compiler that optimizes away global > variables and busts SMP dependent code. I am not going to remove the
The Linux way to handle this is to use gcc memory barriers. mb()/barrier()/wmb()/rmb()/smp_rmb()/smp_wmb() etc. Normally everything that volatile can do can be expressed by them.
On x86 such a memory barrier tells gcc that memory might have been clobbered and needs to be flushed and also prevents the compiler from reordering memory accesses. On other architectures it also forces ordering on the CPU level, although that's not needed on x86 (except in some special situations like using write-combining)
See Documentation/memory-barriers.txt
-Andi
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