Messages in this thread | | | Date | Tue, 9 Apr 2013 21:10:37 -0700 | Subject | Re: [RFC PATCH 3/3] pstore/ram: avoid atomic accesses for ioremapped regions | From | Colin Cross <> |
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On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring <robherring2@gmail.com> wrote: > From: Rob Herring <rob.herring@calxeda.com> > > For persistent RAM outside of main memory, the memory may have limitations > on supported accesses. For internal RAM on highbank platform exclusive > accesses are not supported and will hang the system. So atomic_cmpxchg > cannot be used. This commit uses spinlock protection for buffer size and > start updates on ioremapped regions instead.
I used atomics in persistent_ram to support persistent ftrace, which now exists as PSTORE_FTRACE. At some point during development I had trouble with recursive tracing causing an infinite loop, so you may want to test that calling out to spinlock functions with PSTORE_FTRACE turned on and enabled doesn't cause a problem.
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