linux-kernel - Re: hwrng on 82801EB/ER (ICH5/ICH5R) fails rngtest checks

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Date:	Thu, 27 Jul 2006 14:20:07 +0000
From:	"gmu 2k6" <gmu2006@...il.com>
To:	"Michael Buesch" <mb@...sch.de>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: hwrng on 82801EB/ER (ICH5/ICH5R) fails rngtest checks

On 7/27/06, Michael Buesch <mb@...sch.de> wrote:
> On Wednesday 26 July 2006 21:44, gmu 2k6 wrote:
> > > But could you try the following patch on top of latest git?
> > > It's just a random test, but I think it's worth trying.
> > > Let's see if it works around the issue.
> > >
> > > Index: linux-2.6/drivers/char/hw_random/intel-rng.c
> > > ===================================================================
> > > --- linux-2.6.orig/drivers/char/hw_random/intel-rng.c   2006-06-27 17:48:13.000000000 +0200
> > > +++ linux-2.6/drivers/char/hw_random/intel-rng.c        2006-07-26 17:27:03.000000000 +0200
> > > @@ -104,9 +104,14 @@
> > >         int err = -EIO;
> > >
> > >         hw_status = hwstatus_get(mem);
> > > +       hw_status = hwstatus_set(mem, hw_status & ~INTEL_RNG_ENABLED);
> > > +       hw_status = hwstatus_set(mem, hw_status | INTEL_RNG_ENABLED);
> > > +#if 0
> > > +       hw_status = hwstatus_get(mem);
> > >         /* turn RNG h/w on, if it's off */
> > >         if ((hw_status & INTEL_RNG_ENABLED) == 0)
> > >                 hw_status = hwstatus_set(mem, hw_status | INTEL_RNG_ENABLED);
> > > +#endif
> > >         if ((hw_status & INTEL_RNG_ENABLED) == 0) {
> > >                 printk(KERN_ERR PFX "cannot enable RNG, aborting\n");
> > >                 goto out;
> >
> > well as it didn't work, are you sure it was not intended to be more like this:
> > @@ -104,9 +104,14 @@
> >        int err = -EIO;
> >
> >        hw_status = hwstatus_get(mem);
> > +       hw_status = hwstatus_set(mem, hw_status & ~INTEL_RNG_ENABLED);
> > +       hw_status = hwstatus_set(mem, hw_status | INTEL_RNG_ENABLED);
> > +#if 0
> >        /* turn RNG h/w on, if it's off */
> >        if ((hw_status & INTEL_RNG_ENABLED) == 0)
> >                hw_status = hwstatus_set(mem, hw_status | INTEL_RNG_ENABLED);
> > +#endif
> >        if ((hw_status & INTEL_RNG_ENABLED) == 0) {
> >                printk(KERN_ERR PFX "cannot enable RNG, aborting\n");
> >                goto out;
> >
> > ?
>
> I don't think that makes a difference to the generated code, does it?

I will test it now as you seem to be interested in the results.

actually I was just curious what sense it made to do
hw_status = hwstatus_get(mem);
twice, though I'm not informed about the semantics there so I could be wrong
in interpreting the API on that level.
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