From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Smirl Subject: Re: [Linux-fbdev-devel] Re: Who is stomping PCI config space? Date: Fri, 4 Mar 2005 12:58:02 -0500 Message-ID: <9e473391050304095812a11208@mail.gmail.com> References: <9e4733910503031103552514b9@mail.gmail.com> <1109891245.5611.246.camel@gaston> <9e473391050303161559c17955@mail.gmail.com> <9e47339105030319037f083f7@mail.gmail.com> <1109918459.5610.273.camel@gaston> <16936.20345.249542.65736@xf14.local> Reply-To: Jon Smirl Mime-Version: 1.0 Content-Transfer-Encoding: 7bit In-Reply-To: <16936.20345.249542.65736@xf14.local> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: xorg-bounces@lists.freedesktop.org Errors-To: xorg-bounces@lists.freedesktop.org Content-Type: text/plain; charset="us-ascii" To: Egbert Eich Cc: Jesse Barnes , Xserver development , Linux Fbdev development list In the past Jesse Barnes has suggested a completely different approach to VGA sharing. Instead of each VT trying to control which VGA device is enabled we keep them all turned off. Then on each access we turn VGA support on just long enough for the access and then turn it back off. To make this work we have to have a kernel based 'token' for who has the VGA at the moment. This scheme lets multiuser systems work. For big IA64 machines which can support multiple simultaneous VGAs we just have multiple tokens. We would just ban VGA access from interrupt context, if you really needed VGA access you would use a workqueue which can be scheduled from the interrupt. None of my driver work needs VGA access from interrupt context, is this true for all drivers? I need access to the video hardware, but not access to the VGA support. -- Jon Smirl jonsmirl@gmail.com