<html><head></head><body>VBT is documented by intel-gpu-tools. There's intel_vbt_decode (former intel_bios_decode) available <a href="https://cgit.freedesktop.org/xorg/app/intel-gpu-tools/tree/tools/intel_vbt_decode.c">https://cgit.freedesktop.org/xorg/app/intel-gpu-tools/tree/tools/intel_vbt_decode.c</a> that will print all tables in human readable form.<br>
Regards Patrick<br><br><div class="gmail_quote">Am 4. April 2017 20:45:15 MESZ schrieb Nico Huber <nico.h@gmx.de>:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<pre class="k9mail">Hi Ron,<br /><br />On 04.04.2017 19:46, ron minnich wrote:<br /><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #729fcf; padding-left: 1ex;"> Igor, if you are going to say things like "AFAIK there is no public<br /> description of these tables' layout and contents, only Intel knows how to<br /> build and parse them.", it's really a good idea to back it up with a<br /> primary source, especially since you also use phrases like "I assume" and<br /> "I guess". I am pretty sure you're wrong in this case. The V in VBT, as I<br /> understand it, means VESA, and VESA has been a standard for about 30 years.<br /> <br /> Please, everyone, if you're going to move this conversation forward, you<br /> need to cite primary sources at least, such as this one:<br /> <a href="http://www.petesqbsite.com/sections/tutorials/tuts/vbe3.pdf">http://www.petesqbsite.com/sections/tutorials/tuts/vbe3.pdf</a>.<br /></blockquote><br />now you got confused too. I'll try to clarify.<br /><br />VBE means VESA (Video Electronics Standards Association) BIOS Extension.<br />It's a Video BIOS interface extension (i.e. specifying additional BIOS<br />calls). Don't know if it was public from the beginning (you often have<br />to be a VESA member to get access to their "standards"), but the inter-<br />face is used by many open source programs. It's vendor independent. Also<br />it's off-topic, nobody was discussing it here.<br /><br />As Igor noted, VBE has absolutely nothing to do with VBT.<br /><br />VBT means Video BIOS Table. It's a 100% Intel specific table of confi-<br />guration options for Intel's Video BIOS and Intel's graphics drivers.<br />There is no public documentation, but as it's used by the Linux driver,<br />at least the structure and some of the values are publicly "documented"<br />[1]. Developers of the i915 Linux driver stated that they are not wil-<br />ling to support systems without a VBT. Most features of the i915 driver<br />work without a VBT by chance. But anything board specific, like inte-<br />grated panels in laptops, will likely _not_ work. I'd also expect that<br />they won't count it as a regression if something breaks but would still<br />work with a VBT. (Windows won't even try to get things running without<br />VBT, AFAIK.)<br /><br />An OEM should have access to Intel's binary configuration tool and the<br />specification file for the VBT of his processor's generation. It comes<br />along with the VBIOS, I suppose.<br /><br />Nico<br /><br />PS. Igor, Zoran please write text-only emails or at least make sure the<br /> text version is readable and quotes are visible as quotes.<br /><br />[1]<br /><a href="https://www.kernel.org/doc/html/latest/gpu/i915.html#video-bios-table-vbt">https://www.kernel.org/doc/html/latest/gpu/i915.html#video-bios-table-vbt</a><br /></pre></blockquote></div></body></html>