On 10/22/12 18:52, Jeff VanDellen wrote:
> I've come across the following information which seems relevant in
> regards to Windows 7/2008's UEFI requirements.

(The following passages are from [1], which I've referenced in section
III of [2].)

> 
> "Display at Boot Time
> For a platform that has a console device, the UEFI 2.0 specification
> requires the firmware to implement the Simple Text Output Protocol.
> Optionally, the firmware can also support a graphical protocol. UEFI
> 2.0 defines the Graphic Output Protocol (GOP), and EFI 1.1 defines the
> Universal Graphics Adapter (UGA) Protocol. Windows supports all three
> protocols, but the user experience with each protocol is different.
> For the best experience, if the firmware implements a graphical
> protocol, Windows recommends and prefers the GOP.
> Windows requires a graphical protocol to render glyphs for non-English
> message resources. To do so, the firmware must support the following:
> •     A graphical protocol—either GOP or UGA.
> •     Either 1024x768 display resolution with 32-bit pixel color or
> 800x600 display resolution with 24-bit pixel color.
> 
> If the firmware does not support any of these graphics modes, Windows
> still functions, but all boot display reverts to text mode and
> English.
> Windows 7 and Windows Server 2008 R2 require GOP to display a
> high-resolution, animated image during boot. If GOP is not available,
> Windows uses the video graphics array (VGA) standard to display a
> lower resolution image and a simple progress indicator. For an optimal
> boot experience with these versions of Windows, sealed platforms
> without expansion card slots can safely boot with graphics mode
> enabled and eliminate transitions to text mode.
> Whenever the firmware boot manager hands off execution to a Windows
> EFI application, platform firmware and the firmware boot manager must
> not use the frame buffer for any purpose."

The core of the problem is precisely that: *even though* the OVMF GOP
supports
- 800x600x32,
- 1024x768x24,
- and with my recent patch, 800x600x24,

the windows UEFI installer (the kernel in the WinPE phase) *nonetheless*
requires a VGA BIOS. Ie. not "either-or": "always". This Windows 7 /
Server 2008 R2 bug is what Razvan has repeatedly pointed out on the web,
and what Windows 8 / Windows Server 2012 apparently fix. The latter in
fact rely on the GOP only, as they should. (... until the "real" video
driver is loaded of course.)

Laszlo

[1] http://www.feishare.com/attachments/083_UEFIrequirements.pdf
[2] http://article.gmane.org/gmane.comp.bios.tianocore.devel/799

------------------------------------------------------------------------------
Everyone hates slow websites. So do we.
Make your web apps faster with AppDynamics
Download AppDynamics Lite for free today:
http://p.sf.net/sfu/appdyn_sfd2d_oct
_______________________________________________
edk2-devel mailing list
edk2-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/edk2-devel

Reply via email to