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

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Message-Id: <200607261730.31717.mb@bu3sch.de>
Date:	Wed, 26 Jul 2006 17:30:31 +0200
From:	Michael Buesch <mb@...sch.de>
To:	"gmu 2k6" <gmu2006@...il.com>
Cc:	"Jeff Garzik" <jgarzik@...ox.com>,
	"Philipp Rumpf" <prumpf@...drakesoft.com>,
	"Andrew Morton" <akpm@...l.org>, linux-kernel@...r.kernel.org
Subject: Re: hwrng on 82801EB/ER (ICH5/ICH5R) fails rngtest checks

On Wednesday 26 July 2006 16:52, gmu 2k6 wrote:
> On 7/26/06, Michael Buesch <mb@...sch.de> wrote:
> > On Wednesday 26 July 2006 16:21, gmu 2k6 wrote:
> > > it just outputs this and stops with 2.6.18-rc2-HEAD (see dmesg for hashcode or
> > > whatever that is which is appended as localversion)
> > >
> > > svn:~# hexdump /dev/hwrng
> > > 0000000 ffff ffff ffff ffff ffff ffff ffff ffff
> > > *
> > >
> > > with 2.6.17.6:
> > > svn:~# hexdump /dev/hwrng
> > > 0000000 ffff ffff ffff ffff ffff ffff ffff ffff
> > > *
> > >
> > > this was without any rng-tools installed and no rngd running of course.
> >
> > Hm, so I would say the hardware either broken, or intel
> > changed the way to read the random data from it. But I doubt they
> > would change something like this on the ICH5.
> >
> > Who wrote the ICH driver? Jeff? Philipp?
> > What do you think?
> 
> IIRC it was Jeff.

"What do you think?" was more a question to Jeff or Philipp ;)



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;


-- 
Greetings Michael.
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