Date: Tue, 19 Feb 2013 18:01:01 GMT From: Anton Shterenlikht <mexas@bristol.ac.uk> To: freebsd-x11@freebsd.org, ml@netfence.it Subject: Re: why drm? Message-ID: <201302191801.r1JI11uU020758@mech-cluster241.men.bris.ac.uk> In-Reply-To: <5123A693.3010905@netfence.it>
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Date: Tue, 19 Feb 2013 17:21:39 +0100 From: Andrea Venturoli <ml@netfence.it> To: freebsd-x11@freebsd.org Subject: Re: why drm? On 02/19/13 09:22, Anton Shterenlikht wrote: > > I'm confused about DRM/DRI. Hi Anton. I waited before replying, since I'm no expert on this one; in fact I share some of your doubts. However, since no one else stepped forward, I'll try what little I can. Thanks for taking time to answer. > I've done some brief reading but still > not clear what these do, or > even if DRM and DRI do the same thing? Take a look at this: http://www.bitwiz.org.uk/s/how-dri-and-drm-work.html. I cannot verify if this is current or even correct, but there are some sentences which might answer you: "The Direct Rendering Manager, DRM, is the kernel part of the wider Direct Rendering Infrastructure (DRI)."... "With DRM in place, the X server uses the ioctl interface to pass its commands down to the kernel."... ""DRI" could be taken to mean the overall infrastructure which makes accelerated rendering possible. The DRI interface, which is what this section is about, is specific to X."... "DRI is just one way to use the underlying DRM framework. For instance, there are other graphics systems (such as Wayland) which also use DRM to access the hardware." I'll have a full read later, but what you quote does make some sense. > If I build a kernel with drm: > > # grep drm /root/kernels/BUZI > device drm # DRM core module required by DRM drivers > device i915drm # Intel i830 through i915 > device r128drm # ATI Rage 128 > device radeondrm # ATI Radeon > device viadrm # VIA > # > > (I probably don't need all these drm options) I have a Radeon too, although not the same model you have. I never compiled drm modules into the kernel, they get loaded dynamically. Well, I prefer to link everything I need in the kernel, but I guess I could've done it with modules. > 1. Do I need DRM/DRI. My understanding is > that X will do just as well without it, > perhaps a bit slower. Is that correct? I'm not sure you can run the Radeon driver without drm and radeon modules; for sure you don't need them in the kernel. Well, X certainly work for me with no drm at all. You could also try the VESA driver if speed is not an issue. with vesa I get another error, forgot exactly what, I think something about not finding the colour depth, although I tried all values from 24 down to 1. Do you have a xorg.conf file? If so, what's in Section "Module"? Section "Module" Load "extmod" Load "record" Load "dbe" Load "dri" Load "dri2" Load "glx" EndSection and it all loads fine: (II) "extmod" will be loaded. This was enabled by default and also specified in the config file. (II) "dbe" will be loaded. This was enabled by default and also specified in the config file. (II) "glx" will be loaded. This was enabled by default and also specified in the config file. (II) "record" will be loaded. This was enabled by default and also specified in the config file. (II) "dri" will be loaded. This was enabled by default and also specified in the config file. (II) "dri2" will be loaded. This was enabled by default and also specified in the config file. *skip* (II) LoadModule: "dri" (II) Loading /usr/local/lib/xorg/modules/extensions/libdri.so (II) Module dri: vendor="X.Org Foundation" compiled for 1.7.7, module version = 1.0.0 ABI class: X.Org Server Extension, version 2.0 (II) Loading extension XFree86-DRI (II) LoadModule: "dri2" (II) Loading /usr/local/lib/xorg/modules/extensions/libdri2.so (II) Module dri2: vendor="X.Org Foundation" compiled for 1.7.7, module version = 1.1.0 ABI class: X.Org Server Extension, version 2.0 (II) Loading extension DRI2 > I'd be grateful for any advice or a link > to a relevant existing document. Unfortunately, with recent X, I always found it hard to find documents which could stay "current" for a long time. HTH bye av. P.S. So that other might help you, it would possibly be useful to know which version of FreeBSD you are running. This is 10.0-CURRENT #29 r246370M M refers a patch by John Baldwin because my BIOS is apparently broken. Many thanks again Anton
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