[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] vexpress: Framebuffer broken with KVM enabled
|
From: |
Jan Kiszka |
|
Subject: |
Re: [Qemu-devel] vexpress: Framebuffer broken with KVM enabled |
|
Date: |
Mon, 16 Feb 2015 10:26:07 +0100 |
|
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2015-02-16 10:20, Anup Patel wrote:
> On Mon, Feb 16, 2015 at 2:43 PM, Jan Kiszka <address@hidden> wrote:
>> Hi,
>>
>> next issue related to KVM/QEMU on the TK1: The guest image I'm running
>> gives proper framebuffer output when in emulation mode. Once KVM is
>> enabled, the screen is - at best - only initially updated. Sometimes I
>> see the famous tux images and a bit of the console texts, but usually it
>> stays black. Explanations?
>
> The QEMU accesses Guest Video RAM (or any portion of Guest RAM) as
> cacheable user space memory. The Guest Kernel might access Guest Video
> RAM as non-cacheable to maintain coherency with video device. If this is
> the case then all updates by Guest kernel to Guest Video RAM will not
> be visible to QEMU.
On x86, we manage such RAM as coalesced MMIO region, sync'ing it
periodically or on specific register accesses into the video card model.
I suppose there is nothing like this for the pl111 yet, right?
Jan
signature.asc
Description: OpenPGP digital signature