Messages in this thread | | | Date | Thu, 08 Apr 2010 11:52:02 +0200 | From | Michael Schnell <> | Subject | Re: atomic RAM ? |
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On 04/08/2010 11:28 AM, David Newall wrote: > Will the system use multiple cores? If it's only single core, perhaps > atomic operations are really necessary? At the moment I am just planning a single core NIOS project. But SMP is a decent option for NIOS, as it is no hardware problem - and often has been requested - to design multiple CPUs in a single in such an FPGA and run SMP Linux on it.
OTOH, to do FUTEX in full (MMU) - Linux, atomic operations are definitively necessary, as in Userland you can't disable the interrupt without a Kernel call (which to avoid FUTEX is all about.) Currently the plan with the NIOS (MMU, non-SMP) arch is to simulate atomic operations with the said "atomic region" (as is done with e.g. the BlackFin arch).
(BTW.: when enumerating the ways how atomic macros are done I forgot to mention the "new ARM" method: dedicated "load locked, store conditional" operations that help simulating atomic behavior in user space without the Kernel's help.)
-Michael
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