Re: runtime check for omap-aes bus access permission (was: Re: 3.13-rc3 (commit 7ce93f3) breaks Nokia N900 DT boot)

["Pali Rohár" <pali.rohar@gmail.com>]

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On Saturday 31 January 2015 16:13:39 Matthijs van Duin wrote:
> On 31 January 2015 at 12:34, Pali Rohár <pali.rohar@gmail.com> 
wrote:
> > [  172.923553] Unhandled fault: external abort on
> > non-linefetch (0x1018) at 0xb6f87028 [  172.930664] In-band
> > Error seen by MPU  at address 0
> 
> Also, why is this error so uninformative?  A synchronous abort
> should at least mention the _physical_ address, type of
> access, etc.
> 
> Anyhow, since checking the firewalls/APs to see if you have
> permission will probably only get you yet another fault if
> things are walled off, the robust way of dealing with this
> sort of situation is by probing the device with a read while
> trapping bus faults. This also handles modules that are
> unreachable for other reasons, e.g. being disabled by eFuse.

Just to note that above error output is from device where is 
signed X-Loader which *enable* omap aes support.

So it looks like it is not possible to dump registers which 
should tell you if kernel has permission or not (in L3 firewall).

-- 
Pali Rohár
pali.rohar@gmail.com

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