Re: [RFC] RNG rewrite...

[H. Peter Anvin]

Followup to:  <20051016005341.GB5946@xxxxxxxxxxx>
By author:    Deepak Saxena <dsaxena@xxxxxxxxxxx>
In newsgroup: linux.dev.kernel
> 
> It's a magic regsiter we just read/write and could be done in userspace.
> I also took a look at MPC85xx and it has the same sort of interface but
> also has an error interrupt capability. On second thought a class
> interface is overkill b/c there will only be one RNG per system, so
> I can just do something like watchdogs where we have a bunch of simple
> drivers exposing the same interface. We could do it in user space but
> then we have separate RNG implementations for  x86 and !x86 and I'd
> rather not see that. Can we move the x86 code out to userspace and
> just let the daemon eat the numbers directly from HW? We can mmap() 
> PCI devices, but I don't know enough about x86 to say whether msr 
> instructions can execute out of userspace (or if we want them to...).
> 

MSR instructions cannot execute out of userspace, but the MSR driver
might be possible to use.  It's usually quite slow, however.

	-hpa
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