From owner-freebsd-alpha  Wed May 15 21: 0: 8 2002
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Date: Wed, 15 May 2002 21:00:01 -0700
From: Kris Kennaway <kris@obsecurity.org>
To: John Baldwin <jhb@FreeBSD.org>
Cc: Kris Kennaway <kris@obsecurity.org>,
	Andrew Gallatin <gallatin@cs.duke.edu>, alpha@FreeBSD.org
Subject: Re: memory management fault during netbooting on 4.6-PRERELEASE
Message-ID: <20020515210001.A742@xor.obsecurity.org>
References: <20020515204816.B302@xor.obsecurity.org> <XFMail.20020515235535.jhb@FreeBSD.org>
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On Wed, May 15, 2002 at 11:55:35PM -0400, John Baldwin wrote:
>=20
> On 16-May-2002 Kris Kennaway wrote:
> > On Wed, May 15, 2002 at 11:40:48PM -0400, John Baldwin wrote:
> >=20
> >> > (gdb) l *0xfffffc000056bcc0
> >> > No source file for address 0xfffffc000056bcc0.
> >>=20
> >> Ok, can you do a nm kernel.debug | sort | less and find the two
> >> symbols that that address falls between?
> >=20
> > fffffc000056bca0 t swi_net
> > fffffc000056bd20 T do_sir
>=20
> Ok, swi_net() looks like so (alpha/alpha/iplfuncs.c)
>=20
> static void
> swi_net()
> {
>     u_int32_t bits =3D atomic_readandclear(&netisr);
>     int i;
>=20
>     for (i =3D 0; i < 32; i++) {
>         if (bits & 1)
>             netisrs[i]();
>         bits >>=3D 1;
>     }
> }
>=20
> My guess then is that we tried to execute a netisr() that was
> NULL.  Is this reproducible?

Yes, it seems to be.

> If so, you could try adding a
> a hack to not execute the isr if it's null, i.e.:
>=20
>         if ((bits & 1) !=3D 0 && netisrs[i] !=3D NULL)
>             netisrs[i]();

Will try once the current alpha package build is finished.  Are there
any other diagnostics I can add while I'm in there?

Kris

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