<div class="gmail_quote">On Tue, Feb 24, 2009 at 11:18 AM, Adam Jackson <<a href="mailto:ajax@redhat.com">ajax@redhat.com</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> <div class="Ih2E3d">On Tue, 2009-02-24 at 10:02 -0500, Fulko Hew wrote: > I've been curious about dual-headed operation for some time now, > and either because I'm using old software, or my hardware doesn't > support it, I've never been able to get it to work. It could also > be because I don't know, or can't properly perform the correct > magic incantations. > > But the first question is always: > 'How can I tell if my hardware is capable of dual-headed operation'? </div>If it's an intel chip, or a radeon chip, or an nvidia chip newer than a geforce 7 series, then it is dual-head capable. nvidia chips should get even more support as we move to nouveau. There may be _limitations_ on how dualhead you can be. For example: <div class="Ih2E3d"> > 00:02.0 VGA compatible controller: Intel Corporation Mobile > 945GM/GMS, 943/940GML Express Integrated Graphics > Controller (rev 03) </div>Intel 915 and 945 series chips have a coordinate limit at 2048 pixels wide. This manifests in ugly ways, but the short answer is that if you're trying to do something wider than that (like two 1280x1024 displays next to each other) then it's not going to work right. That's partly a hardware limit, and partly a software limit that's really hard to fix.</blockquote><div> So if I read you right... Since I have a 1600x1050 LCD display... and there is a 2048 limit, then my 2nd display could only be 448 pixels wide? ;-( I would have expected dual-head to imply (given the 2048 restriction) that I could have two displays up to 2048 wide. ie. an internal display at 1600x1050 and an external display at 1280x1024 (for example) Right now, I haven't figured out a way to get the VGA connector to emit 'different' data than whats on the LCD. </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">We also still don't do memory management as well as we ought to, which means you may need to explicitly set the Virtual size to allocate in the config file to get the size you want.</blockquote><div> Forgive my ignorance, but why should I care about 'virtual size'? I thought 'virtual size' simply allowed the 'physical screen' to scroll around on the 'virtual screen'. Or does it mean that I need a 'really big' virtual screen that has two physical screens consuming parts of that 'virtual screen'? </div></div>