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

[Pavel Machek <pavel@ucw.cz>]

Hi!

On Sun 2015-02-01 09:56:28, Pali Rohár wrote:
> On Sunday 01 February 2015 02:36:06 Matthijs van Duin wrote:
> > On 31 January 2015 at 20:06, Pali Rohár <pali.rohar@gmail.com> 
> > wrote:
> > > I have configured two testing N900 devices. One with signed
> > > bootloader which enable omap aes support and one device with
> > > signed bootloader which does not enable omap aes support.
> > 
> > I'm probably missing some context here, but why not just use
> > the one with aes support? Alternatively, one may argue that
> > it's the bootloader's job to provide the kernel with an
> > accurate device tree. (Though one may equally well argue that
> > it would be nice to avoid having to customize the device tree
> > for every feature-flavor of a processor, especially if this
> > depends on how it's initialized.)
> > 
> 
> Nokia X-Loader is closed source and signed. So we cannot modify 
> it. And it is responsible for configuring L3/L4 firewall.
> 
> Year ago it was possible to find on internet signed X-Loader for 
> N900 which enable omap aes support (for testing purpose together 
> with open source linux kernel modules), but it is unofficial and 
> I think there only too few people who flashed it into N900 nand. 
> If somebody needs binaries I have backup all of them.
> 
> More info about that aes enabled X-Loader:
> http://maemo.org/community/maemo-developers/n900_aes_and_sha1-md5_hw_acceleration_drivers/
> 
> Majority of users use only official X-Loader which does not 
> enable aes support so we cannot enable kernel modules (cause 
> crashes). And also we cannot force users to flash some unofficial 
> binary into their device...

BTW... it would be interesting to know... are you doing some
heavy crypto processing on N900? Are the accelerated drivers faster
than non-accelerated ones? Because the link above says they are
slower...

# Eric Wheeler
# ...
# Hey guys, I have omap-aes compiled for my kernel and appears to be
# working.
# 
# I do not understand why non-accelerated software-crypto is faster than
# the omap-aes hardware acceleration:
# 
# mmcblk0 onboard 32GB: read=21.76MB/s write=12.97MB/s
# aes_generic crypto: read= 8.47 write= 5.54
# omap-aes hw crypto: read= 6.31 write= 5.45
# 
# mmcblk1 uSD 16GB Class 10: read=16.05MB/s write=16.47MB/s
# aes_generic crypto: read= 7.96 write= 7.43
# omap-aes hw crypto: read= 6.67 write= 7.18

Best regards,
									Pavel
-- 
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