From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Lin Ming <mlin@ss.pku.edu.cn>
Cc: Ian Campbell <Ian.Campbell@citrix.com>,
Andrew Cooper <Andrew.Cooper3@citrix.com>,
"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [Xen-devel] [PATCH] xen/apic: implement io apic read with hypercall
Date: Mon, 23 Apr 2012 11:11:23 -0400 [thread overview]
Message-ID: <20120423151123.GC24481@phenom.dumpdata.com> (raw)
In-Reply-To: <CAF1ivSamaYzQDwjFqRGrnQ+fCr0D4vLGuG4JRBZ3_GD_y8yY=A@mail.gmail.com>
> >> > How about return -1 on error?
> >> > The calling function can check -1 for error.
> >>
> >> Isn't -1 potentially (at least theoretically) a valid value to read from
> >> one of these registers?
> >
> > Yeah, but then we are back to crashing at bootup (with dom0) :-)
> >
> > Perhaps the fallback is to emulate (so retain some of the original code)
> > as we have been since .. uh 3.0?
>
> Do you mean the return value of io_apic_read in 3.0?
No. I meant that we would continue to emulate. The improvement
is that now we do:
if (reg == 0x1)
return 0x00170020;
else if (reg == 0x0)
return apic << 24;
instead of 0xfdfdfdfd.
> It's 0xffffffff.
Now it is 0xfdfdfdfd.
I am suggesting that instead of BUG_ON(), we fallback to do returning
an emulatated IO_APIC values - like the ones that this original patch
cooked up..
next prev parent reply other threads:[~2012-04-23 15:11 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-20 9:25 [PATCH] xen/apic: implement io apic read with hypercall Lin Ming
2012-04-20 9:58 ` [Xen-devel] " Andrew Cooper
2012-04-20 11:13 ` Lin Ming
2012-04-20 12:38 ` Ian Campbell
2012-04-20 12:52 ` Jan Beulich
2012-04-20 12:53 ` Andrew Cooper
2012-04-20 13:12 ` Ian Campbell
2012-04-20 13:20 ` Andrew Cooper
2012-04-20 14:50 ` Lin Ming
2012-04-20 14:59 ` [Xen-devel] " Jan Beulich
2012-04-20 15:06 ` Ian Campbell
2012-04-20 15:39 ` Lin Ming
2012-04-20 16:43 ` Konrad Rzeszutek Wilk
2012-04-20 16:41 ` Konrad Rzeszutek Wilk
2012-04-23 8:42 ` Lin Ming
2012-04-23 15:11 ` Konrad Rzeszutek Wilk [this message]
2012-04-24 14:43 ` Lin Ming
2012-04-24 16:23 ` Konrad Rzeszutek Wilk
2012-04-25 10:06 ` Lin Ming
2012-04-26 15:33 ` Konrad Rzeszutek Wilk
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