Re: [stable] [PATCH 46/61] fix Intel RNG detection

From: Jan Beulich
Date: Mon Nov 27 2006 - 03:29:54 EST

>>> Dave Jones <davej@xxxxxxxxxx> 24.11.06 21:27 >>>
>On Wed, Nov 22, 2006 at 08:53:08AM +0100, Jan Beulich wrote:
> > >It does appear to work w/out the patch. I've asked for a small bit
> > >of diagnostics (below), perhaps you've got something you'd rather see?
> > >I expect this to be a 24C0 LPC Bridge.
> >
> > Yes, that's what I'd have asked for. If it works, I expect the device
> > code to be different, or both manufacturer and device code to be
> > invalid. Depending on the outcome, perhaps we'll need an override
> > option so that this test can be partially (i.e. just the device code
> > part) or entirely (all the FWH detection) skipped.
> > The base problem is the vague documentation of the whole
> > detection mechanism - a lot of this I had to read between the lines.
>The bug report I referenced came back with this from that debug patch..
>intel_rng: no version for "struct_module" found: kernel tainted.
>intel_rng: pci vendor:device 8086:24c0 fwh_dec_en1 80 bios_cntl_val 2 mfc cb dvc 88
>intel_rng: FWH not detected

Okay, this means the lock is being set by the BIOS, which disallows
disabling BIOS (and thus accessing the FWH). By default, I think it
is correct to consider the RNG not present in this case, however as
previously indicated I think we should provide a way to force
skipping the FWH test (with three levels - carry out, skip always, or
skip if BIOS locked).
I'll prepare a patch as soon as I can, but it might take a few days
until I get to it.

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