error message at boot - Red Hat 5.2

error message at boot - Red Hat 5.2

Post by Gavin Maxwel » Wed, 10 Mar 1999 04:00:00



I was wondering if anyone knows how to resolve the error message at boot
time that is associated with an Intel processor:

Intel Pentium with F0 0F bug, workaround enabled

Thanks

Gavin M. (nexus)

 
 
 

error message at boot - Red Hat 5.2

Post by Pete » Wed, 10 Mar 1999 04:00:00



> I was wondering if anyone knows how to resolve the error message at boot
> time that is associated with an Intel processor:

> Intel Pentium with F0 0F bug, workaround enabled

> Thanks

> Gavin M. (nexus)

AFAIK this is not an error, merely a way the OS gets around a bug in the
actual Intel CPU chip that has to do with dealing with F0 0F somewhere,
it's a fairly well known fault in the chip design that probably doesn't
effect CPU performance that much (other than the occasional - and rare -
crash). I get that message too, and it just means that Linux recognises
this error in the chip and makes sure it doesn't get used in that way.

Pete

PS: I don't actually know what the F0 0F bug is in terms of what it
does, but I'd be interested to know.

--
remove 'x' for email

 
 
 

error message at boot - Red Hat 5.2

Post by **Nick Brow » Wed, 10 Mar 1999 04:00:00


There was a flap a couple of years back when it was discovered that
certain (illegal) opcodes beginning with the bytes F0 0F, could cause a
Pentium to crash/hang, even when executed from non-privileged modes.
Intel patched the chip from a certain revision.  For earlier chips,
its's up to the OS to install handlers to stop the crash.

I think the message is fairly self-explanatory - "workaround enabled" -
no ?  Oh well.

--
---------------------------------------------------------------
|\ | o  _ |/                               Life's like a jigsaw
| \| | |_ |\                          You get the straight bits
                    But there's something missing in the middle

Nick Brown, Strasbourg, France (Nick(dot)Brown(at)coe(dot)fr)
---------------------------------------------------------------

 
 
 

error message at boot - Red Hat 5.2

Post by Jason Cliffor » Wed, 10 Mar 1999 04:00:00



> PS: I don't actually know what the F0 0F bug is in terms of what it
> does, but I'd be interested to know.

There are a series of registers in the Intel Pentium CPU addressed from
F0 0F ?? ?? that will immediately halt the CPU if you address them.

This was a big issue early last year when it was discovered and prompted
some very hurried work to get fixes out for Linux and *BSD systems. An
initial patch for Linux was available within 5 days of the bug being
discovered and a day after that a fix was available for *BSD systems. The
*BSD fix was slightly better.

Intel had gotten involved by this stage and helped to rewrite the fixes
properly which took about another week.

The fix involves turning off access to L2 cache under some circumstances
IIRC so it does have a small performance impact.

This bug is potentially quite serious although not to anyone running a
recent Linux or *BSD kernel - ie for Windows users as a web site would be
set up to cause your system to simply hang. You get no warning or message
log.

Jason Clifford
Definite Linux Systems
http://definite.ukpost.com/

 
 
 

error message at boot - Red Hat 5.2

Post by Michael McConnel » Wed, 10 Mar 1999 04:00:00




> > PS: I don't actually know what the F0 0F bug is in terms of what it
> > does, but I'd be interested to know.

> There are a series of registers in the Intel Pentium CPU addressed from
> F0 0F ?? ?? that will immediately halt the CPU if you address them.

F0 0F C7 C8

-- Michael (who uses an AMD K6 so isn't affected ;)
Eridani Star System  --  The Most Up-to-Date Red Hat Linux CDROMs Available

 
 
 

error message at boot - Red Hat 5.2

Post by Jason Cliffor » Thu, 11 Mar 1999 04:00:00



> > There are a series of registers in the Intel Pentium CPU addressed from
> > F0 0F ?? ?? that will immediately halt the CPU if you address them.

> F0 0F C7 C8

It is actually a range of (IIRC) 16 opcodes starting at that address.

In any event it is utterly immaterial for Linux users after 2.0.35.

Jason Clifford
Definite Linux Systems
http://definite.ukpost.com/

 
 
 

1. Help Installing Red Hat 5.2, when installing from boot disk I get hard drive error.

I have three hard drives. When I put the boot disk at I boot. I choose
normal setup (Simply hiting enter) it gives me an error. It says detecting
HDD the a bunch of AAaAaaAAAAaaAA symbols. Then if keeps repeating
IF_unexpected_error status 0X58 (Or something like this) I all so tried to
go to resuce and expert, which neither worked.
                    Thanks for your time

2. Developing Device Drivers for Linux?

3. Red Hat 7.3 boot After Installation; GRUB Hard Disk Error Message

4. linux setup

5. SATAN: Questions

6. Red Hat 5.2 Loadlin HOWTO (WAS: Can't install LILO from RH 5.2)

7. Microtech and Linux

8. Can't boot Win98 after installing Linux Red Hat 5.2

9. Red Hat 5.2 Freezes during boot

10. Window NT 4 & Red Hat Linux 5.2 & Boot Magic

11. Boot problems Linux (Red Hat 5.2) with NT loader

12. linux boot red hat 5.2 apollo