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From: Avi Kivity <avi@redhat.com>
To: Gerhard Wiesinger <lists@wiesinger.com>
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: Re: [Qemu-devel] Re: QEMU-KVM and video performance
Date: Wed, 21 Apr 2010 23:49:45 +0300	[thread overview]
Message-ID: <4BCF64E9.4090909@redhat.com> (raw)
In-Reply-To: <alpine.LFD.2.00.1004212010270.14758@bbs.intern>

On 04/21/2010 09:14 PM, Gerhard Wiesinger wrote:
>
> Can you explain which code files/functions of KVM is involved in 
> handling VGA memory window and page switching through the port write 
> to the VGA window register (or is that part handled through QEMU), so 
> a little bit architecture explaination would be nice?

qemu hw/vga.c and hw/cirrus_vga.c.  Boring functions like 
vbe_ioport_write_data() and vga_ioport_write().

>
> BTW: In which KVM code parts is decided where "direct code" or an 
> "emulated device code" is used?
>

Same place.  Look for calls to cpu_register_physical_memory().  If the 
last argument was obtained by a call to cpu_register_io_memory(), then 
all writes trap.  Otherwise, it was obtained by qemu_ram_alloc() and 
writes will not trap (except the first write to a page in a 30ms window, 
used to note that the page is dirty and needs redrawing).


-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

  reply	other threads:[~2010-04-21 20:49 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-04-19 19:14 [Qemu-devel] QEMU-KVM and video performance Gerhard Wiesinger
2010-04-21  8:59 ` [Qemu-devel] " Avi Kivity
2010-04-21 10:08   ` Jamie Lokier
2010-04-21 10:49     ` Avi Kivity
2010-04-21 18:14       ` Gerhard Wiesinger
2010-04-21 20:49         ` Avi Kivity [this message]
2010-04-22  5:37           ` Gerhard Wiesinger
2010-04-22  6:57             ` Avi Kivity
2010-04-21 18:39       ` Jamie Lokier
2010-04-21 20:51         ` Avi Kivity
2010-04-21 21:19           ` Jamie Lokier
2010-04-22  5:44           ` Gerhard Wiesinger
2010-05-12 10:34             ` Jamie Lokier
2010-04-21 18:09   ` Gerhard Wiesinger
2010-04-21 18:33     ` Jamie Lokier
2010-04-21 18:50       ` Gerhard Wiesinger
2010-04-21 18:53         ` Jamie Lokier
2010-04-21 19:08           ` Gerhard Wiesinger
2010-04-21 21:30             ` Jamie Lokier
2010-04-22  6:12               ` Gerhard Wiesinger
2010-05-12 10:23                 ` Jamie Lokier
2010-04-21 20:56         ` Avi Kivity
2010-04-22  6:04           ` Gerhard Wiesinger
2010-04-22  7:03             ` Avi Kivity
2010-05-09 19:35               ` Gerhard Wiesinger
2010-05-10  7:32                 ` Avi Kivity
2010-05-12  6:14                   ` Gerhard Wiesinger
2010-05-12  6:39                     ` Avi Kivity
2011-02-18  7:32                       ` [Qemu-devel] Re: QEMU-KVM and video performance - Update Gerhard Wiesinger

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