Re: cpu reset on laptops and microcode update.

From: quasi@quasisoft.com
Date: Thu Sep 21 2000 - 08:01:08 EST


> > Tigran Aivazian <tigran@veritas.com> on 21/09/2000 09:50:53
> >
> > Please respond to Tigran Aivazian <tigran@veritas.com>
> >
> > To: linux-kernel@vger.kernel.org
> > cc: (bcc: Richard J Moore/UK/IBM)
> > Subject: cpu reset on laptops and microcode update.
> >
> > Hi guys,
> >
> > A long time ago I noticed a curious feature on my Dell Latitude CPx
> > H-450GT laptop - rebooting it via "shutdown -r now" (and therefore going
> > through BIOS) does not discard the microcode applied to the CPU. But I
> > would expect it to be discarded as prescribed by Intel manuals, on #RESET.
> >
> > Does it mean that rebooting a laptop does not actually ever reset the
> > CPU? (this would imply that the BIOS is also a protected mode software?)
> >
> > Of course, doing "shutdown -h now" and switching off the power does
> > discard the microcode as expected.
> >
> > Any thoughts? I post on linux-kernel because, potentially, your thoughts
> > may become relevant to the content of arch/i386/kernel/microcode.c which
> > is part of Linux kernel :)
> >
> > Regards,
> > Tigran
> >
> I wouldn't have expected a reset to be done on shutdown -r since that
> doesn't force POST to run. My guess is that we go directly to the BIOS to
> read the bootstrap (INT 19 is it??)
>
>
> Richard Moore - RAS Project Lead - Linux Technology Centre.
>
> http://oss.software.ibm.com/developerworks/opensource/linux
> Office: (+44) (0)1962-817072, Mobile: (+44) (0)7768-298183
> PISC, MP135 Galileo Centre, Hursley Park, Winchester, SO21 2JN, UK

I was curious about this when with OS/2, the Win-OS2 media player would not
stop when I gave it the three-finger-salute while it was still playing a
CD-ROM, that is, until it began to re-boot. When it re-boots, the microcode
should get replaced during the bootstrap process.

Douglas Ostling

-- 
http://www.quasisoft.com
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
The enclosed document(s) are only meant for the use of the addressee(s).
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/



This archive was generated by hypermail 2b29 : Sat Sep 23 2000 - 21:00:24 EST