Date: Sat, 4 Apr 2015 18:27:11 +1100 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Rui Paulo <rpaulo@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r281059 - head/sys/boot/efi/boot1 Message-ID: <20150404175620.V1951@besplex.bde.org> In-Reply-To: <201504040427.t344RtGZ095522@svn.freebsd.org> References: <201504040427.t344RtGZ095522@svn.freebsd.org>
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On Sat, 4 Apr 2015, Rui Paulo wrote: > Log: > boot1 EFI: reset the screen and select the best mode. > > It's necessary to reset the screen to make sure any vendor pixels are > gone when we start boot1. In the Lenovo X1 (3rd gen), this is the > only way to clear the screen. Previously, the Lenovo logo would only > disappear after the kernel started scrolling the display. > > After resetting the screen, EFI could put us in the worst LCD mode > (oversized characters), so we now find the largest mode we can use and > hope it's the most appropriate one (it's not trivial to tell what's > the correct LCD resolution at this point). It's worth noting that the > final stage loader has a 'mode' command that can be used to switch > text modes. :-(. I just complained about the bug that vt (on non-EFI) clears the screen where sc carefully preserves the screen in its history buffer. For graphics mode, determining the resolution is the trivial part :-). You also need OCR or something to translate the pixels into the format of your history buffer. Don't forget to fetch Lenevo's history buffer and translate it into your format :-). I don't have problems with boot logos except when the battery dies, since I turn them off until the CMOS forgets, but lose boot messages in another way from newer monitors blanking the screen after mode switches for much longer than older monitors. I expected newer systems to "fix" this by using the same graphics mode for the whole boot. Resetting the screen is even worse than clearing. Whole boots should take a second or 2. I don't get close to that. More like 20. But with the monitor blanking the screen for 5+ seconds afer every mode switch, even a 20-second boot gives almost no time for reading its messages. Saving the messages in history buffers or booting with -p becomes more important. Bruce
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