LCD Support in kernel

Henrik W Lund henrik.w.lund at
Thu Sep 16 11:19:38 PDT 2004

Tim Pushor wrote:


> I would also have to make sure that the USB subsystem (and probably 
> the serial devices as AFAICT the USB driver for the lcd looks like a 
> serial port to applications) was loaded as early on as I could so I 
> could use it for most of the FreeBSD startup - and what about the 
> shutdown? Will the device exist and work when the kernel is in the 
> 'halted' state?


As far as I know, stuff that you put into the kernel config file gets 
compiled into the kernel. That is, their services are available from the 
moment the kernel is loaded. I guess you would want all things USB 
compiled into the kernel, but it still leaves the issue of "how early do 
you want to be able to output to the screen?".

An RCng script immediately comes to mind, but I don't know if that's 
early enough. Some heavy kernel modding seems to be required if you want 
to output to the screen any earlier than that. Same thing with the 
shutdown. If you're feeling insane ( ;-) ) you could modify init to 
output to it. That's about as early (and late) as it gets, I guess.

Play around with the loadable module first, get it working, worry about 
the other stuff later. And at that time, you could ask -hackers, where 
you'll undoubtedly find much more qualified people than me (although I'm 
getting there ;-) ).

-Henrik W Lund

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