Hi Alexey, On 01-09-2017 12:48, Alexey Brodkin wrote: > Hi Jose, > > On Fri, 2017-09-01 at 12:39 +0100, Jose Abreu wrote: >> I recently came upon a scenario where I would get a double fault >> after a machine check error. It turns out that for Ksymbol lookup >> to work with modules we need to have MMU enabled because module >> address is mapped in the cached space. >> >> This patch re-enables the MMU before start printing the stacktrace >> making stacktracing of modules work upon a fatal exception. > I'm wondering how do we end up with MMU disabled? > From ARC700 databook I cannot find any condition on which MMU could be > silently disabled by hardware and IIRC there's no code in Linux kernel > that disables MMU. According to ARC 700 databook a machine check exception causes Global TLB enable to be cleared. (See ARC 700 databook, page 687). Best regards, Jose Miguel Abreu > > -Alexey
