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From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Lin Ming <mlin@ss.pku.edu.cn>
Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>,
	"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
	Ian Campbell <Ian.Campbell@citrix.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: Thu, 26 Apr 2012 11:33:46 -0400	[thread overview]
Message-ID: <20120426153346.GC26830@phenom.dumpdata.com> (raw)
In-Reply-To: <CAF1ivSYFp7duSCNb+_5teM83icx1O-rY0YVFm7Laq_JLZuzerw@mail.gmail.com>

> >>
> >> unsigned int xen_io_apic_read(unsigned apic, unsigned reg)
> >> {
> >>         struct physdev_apic apic_op;
> >>         int ret;
> >>
> >>         apic_op.apic_physbase = mpc_ioapic_addr(apic);
> >>         apic_op.reg = reg;
> >>         ret = HYPERVISOR_physdev_op(PHYSDEVOP_apic_read, &apic_op);
> >>         if (!ret)
> >>                 return apic_op.value;
> >>
> >>         /* emulate register */
> >>         if (reg == 0x1)
> >>                 return 0x00170020;
> >>         else if (reg == 0x0)
> >>                 return apic << 24;
> >>         else
> >>                 return -1;
> >
> >        return 0xfd;
> 
> Where does this magic number 0xfd come from?
> 
> Both native_io_apic_read and xen_io_apic_read does not return 0xfd on error.

That is correct. But that is what it should have been. Suresh
pointed that out sometime and I managed to lose that part in one of the
commits. The earlier patch of this version did that.

Thought thinking about it this some I am not sure if 0xff is a better
choice... In the end it probably does not matter the slighest.


WARNING: multiple messages have this Message-ID (diff)
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Lin Ming <mlin@ss.pku.edu.cn>
Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>,
	"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
	Ian Campbell <Ian.Campbell@citrix.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] xen/apic: implement io apic read with hypercall
Date: Thu, 26 Apr 2012 11:33:46 -0400	[thread overview]
Message-ID: <20120426153346.GC26830@phenom.dumpdata.com> (raw)
In-Reply-To: <CAF1ivSYFp7duSCNb+_5teM83icx1O-rY0YVFm7Laq_JLZuzerw@mail.gmail.com>

> >>
> >> unsigned int xen_io_apic_read(unsigned apic, unsigned reg)
> >> {
> >>         struct physdev_apic apic_op;
> >>         int ret;
> >>
> >>         apic_op.apic_physbase = mpc_ioapic_addr(apic);
> >>         apic_op.reg = reg;
> >>         ret = HYPERVISOR_physdev_op(PHYSDEVOP_apic_read, &apic_op);
> >>         if (!ret)
> >>                 return apic_op.value;
> >>
> >>         /* emulate register */
> >>         if (reg == 0x1)
> >>                 return 0x00170020;
> >>         else if (reg == 0x0)
> >>                 return apic << 24;
> >>         else
> >>                 return -1;
> >
> >        return 0xfd;
> 
> Where does this magic number 0xfd come from?
> 
> Both native_io_apic_read and xen_io_apic_read does not return 0xfd on error.

That is correct. But that is what it should have been. Suresh
pointed that out sometime and I managed to lose that part in one of the
commits. The earlier patch of this version did that.

Thought thinking about it this some I am not sure if 0xff is a better
choice... In the end it probably does not matter the slighest.

  reply	other threads:[~2012-04-26 15:39 UTC|newest]

Thread overview: 22+ 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 14:50             ` 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
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 [this message]
2012-04-26 15:33                     ` Konrad Rzeszutek Wilk

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