i.MX53QSB port + IOmem access

Andy Wagner rootless at att.net
Tue Aug 7 22:41:56 CEST 2012

Clearing sp for opacr21 allows the access to complete without fault.
It would be very nice if the sp could remain enabled and have the
fault handler trap to supervisor so that hardware enforcement can
be leveraged as well as software resource allocation check.

Since mprot and opacr assignments are SoC specific this
would have to be implemented as part of the BSP framework perhaps
over complicating the issue. Preference is to keep things simple
and probably leave in the underlying linux, where the drivers
are located <executing code localization>, without making fiasco
or l4 more aware of the hardware than necessary. Instruction
emulation could be a bit messy due to differing memory maps
between faulting and exception handling contexts.

Most simply, the sp bits can be cleared by a call into
the bsp and leave the boot loader alone.

Many thanks for your help and insight. Work now proceeds to migrate
the drivers.

thanks & best regards,

 >I'd guess that access from user-mode is the 'problem' here. Could you
 >check the setting of AIPSTZ_OPACR21 and possibly adapt accordingly?

Adam                 adam at os.inf.tu-dresden.de
   Lackorzynski         http://os.inf.tu-dresden.de/~adam/

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