Date: Tue, 14 Dec 2004 16:10:34 -0800 From: Kris Kennaway <kris@obsecurity.org> To: Nate Lawson <nate@root.org> Cc: John Baldwin <jhb@FreeBSD.org> Subject: Re: cvs commit: src/sys/i386/i386 vm_machdep.c Message-ID: <20041215001034.GA60875@xor.obsecurity.org> In-Reply-To: <41BF6F44.2090407@root.org> References: <200411300618.iAU6IkQX065609@repoman.freebsd.org> <200412141333.06213.jhb@FreeBSD.org> <41BF48D4.8080305@root.org> <200412141719.10701.jhb@FreeBSD.org> <41BF6F44.2090407@root.org>
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--+QahgC5+KEYLbs62 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Dec 14, 2004 at 02:55:00PM -0800, Nate Lawson wrote: > >Erm, well, that's not always easy since sometimes when you panic you can= 't=20 > >talk to the other CPUs for whatever reason. Putting back the proxy rese= t=20 > >doesn't hurt for now but does restore functionality in at least some=20 > >cases. I'd rather have that then certain hard panics not get into ddb= =20 > >because we couldn't get onto the BSP to run ddb. >=20 > Perhaps you could give me some pointers on what is counted on to be=20 > working when panic() is called? I can't come up with a situation where= =20 > the proxy code couldn't be used upon entry to ddb. If there were any=20 > cases like this, the proxy code wouldn't work for cpu_reset() either.=20 > Also, in such a case, it's hard to see how ddb could be usable since it= =20 > tries to stop other processors, which requires similar code to the proxy. >=20 > Or in other words, if you have enough capability to call panic() or=20 > break to ddb, then you have enough resources to do an IPI and get onto=20 > the BSP. NB: DDB often isn't usable on SMP machines thesedays, and will hang when a panic tries to enter it. Kris --+QahgC5+KEYLbs62 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.6 (FreeBSD) iD8DBQFBv4D5Wry0BWjoQKURAp+3AJ4wzQwBNTueOPfkIP2Y0kiN+aRbhgCfW4tH qEj3YbkTMzKmLsY4W8EcEEI= =gU6p -----END PGP SIGNATURE----- --+QahgC5+KEYLbs62--
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