From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Liu, Jinsong" <jinsong.liu@intel.com>
Subject: RE: [PATCH] Fix hvm vcpu hotplug bug
Date: Thu, 19 Aug 2010 10:20:22 +0800
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To: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: "Jiang, Yunhong" <yunhong.jiang@intel.com>, "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, "Li, Xin" <xin.li@intel.com>, Keir Fraser <keir.fraser@eu.citrix.com>
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Ian Jackson wrote:
> Liu, Jinsong writes ("RE: [Xen-devel] [PATCH] Fix hvm vcpu hotplug
> bug"):=20
>> I think qemu-xen should add this logic level, so that it can support
>> more gpe events in the future.
>=20
> Yes.  But what clears the interrupt ?  Is it edge or level triggered ?
>=20

SCI is a shareable level interrupt.
Per my understanding, sci-gpe logic is like

                                                  |------- gpe_sts x
                                        |-----AND
                                        |         |------- gpe_en x
sci int                               |
------------------------------------ OR    ......
(wired to i8259[9] etc)         |
                                        |         |------- gpe_sts y
                                        |-----AND
                                                  |------- gpe_en y

Currently qemu-xen didn't have 'gep event x OR gpe event y --> sci' logic, =
it should add this logic level.

To clear the interrupt:
1). gpe_sts x & gpe_en x --> low gpe event x
2). all gpe events low --> low sci
(low is of logic meaning here, not real electric value)

Thanks,
Jinsong