Re: explicit refresh?

[Lennart Sorensen]

On Wed, Feb 08, 2017 at 09:29:36AM +0100, Laszlo Ersek wrote:
> Hi,
> 
> this is a dumb question and it's not appropriate for a development
> mailing list, but I couldn't find "grub-user" or "grub-users", so I'll
> ask here anyway...
> 
> My laptop is connected to my workstation via USB-serial (USB for the
> laptop, serial for the workstation). Sometimes, by the time the laptop
> comes up and starts "screen", for viewing the serial output from the
> workstation, the workstation is already displaying the grub menu.
> Occasionally in this case, I can't see anything at all, there's no grub
> countdown, the cursor up/down keys do nothing (they certainly don't
> refresh the screen), but if I blindly press Enter, then the selected
> kernel entry is booted okay (and that kernel does produce serial output,
> and takes the LUKS password from serial fine as well).
> 
> So, Q1: what could cause the loss of serial output from grub when I
> connect to it "too late"?
> 
> Q2: when that happens, can I press something like C-r to force a full
> serial / screen refresh?
> 
> I know that USB-serial adaptors are generally wacky, but this is a
> Prolific PL2303 adaptor which is (to my knowlede) usually considered
> reliable. Plus, my laptop has no physical RS/232 port (shame on you, all
> laptop vendors of today!), so this is the best I can do.

Actually I would say PL2303 are usually considered quite unreliable.
Doesn't help that there are lots of fakes on the market that are even
worse.

-- 
Len Sorensen