RE: another testmgr question

[Pascal Van Leeuwen <pvanleeuwen@insidesecure.com>]

> All userland clients of the in-kernel crypto use it specifically to
> access h/w accelerators, given that software crypto doesn't require
> the higher privilege level (no point in issuing those AES CPU
> instructions from the kernel if you can issue them in your program
> directly)
>
> Basically, what is used is a socket interface that can block on
> read()/write(). So the userspace program doesn't need to be aware of
> the asynchronous nature, it is just frozen while the calls are being
> handled by the hardware.
>
With all due respect, but if the userland application is indeed
*frozen* while the calls are being handled, then that seems like its
pretty useless - for symmetric crypto, anyway - as performance would be
dominated by latency, not throughput.
Hardware acceleration would almost always lose that compared to a local
software implementation.
I certainly wouldn't want such an operation to end up at my driver!

Which brings up a question: is there some way for a driver to indicate
something like "don't use me unless you can seriously pipeline your
requests"?

Regards,
Pascal van Leeuwen
Silicon IP Architect, Multi-Protocol Engines @ Inside Secure
www.insidesecure.com