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From: | Paolo Bonzini |
Subject: | Re: [Qemu-devel] [v5][PATCH 0/5] xen: add Intel IGD passthrough support |
Date: | Wed, 25 Jun 2014 11:54:22 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 |
Il 25/06/2014 11:50, Chen, Tiejun ha scritto:
For past devices, we know which BARs they use. For future devices, it would be nice if the PCH/MCH backdoor was specified so that we know they will leave a free BAR for virtualization.Now I'm a bit confused about BAR here. You're saying we will reserve a free BAR to address those information to expose to guest, but which device does this free BAR belong to? The video device? Or PCH/MCH?
The video device. If the host device does not have the BAR (which will be the common case), QEMU can emulate it like this:
- offsets 0x0000..0x0fff map to configuration space of the host MCH - offsets 0x1000..0x1fff map to configuration space of the host PCH Of course this is only limited to offsets that are needed by the driver. Paolo
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