On Thu, 2015-01-08 at 09:58 +0000, Markus Stockhausen wrote: > Hello, > > I developed a SHA224/256 kernel crypto module with SPE instructions. > The result looks quite promising (~ +50% speedup). Nevertheless the > flooding of kernel messages "SPE used in kernel" makes me feel > uncomfortable. > > My findings so far: > > - I can configure the kernel with "SPE support". > - arch/powerpc/kernel/head_fsl_booke.S suggests that the message is > triggerd unconditionally whenwever we make use of SPE in kernel. > - There exists a function enable_kernel_spe() but I don't know how > this could help me in my work. > > I guess I need some kind of "brackets" around my coding to make sure > the upper 32 bit of the registers are stored correctly during task switch. > Or is the use of SPE instructions inside the kernel totally forbidden? Any > expert with some helpful advise?
You need to disable preemption, call enable_kernel_spe(), and finish using SPE before you enable preemption. This assumes that SPE is never used from interrupt context. Be careful to not disable preemption for too long. -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev