[U-Boot-Users] silent console, nulldev and CONFIG_AUTOBOOT_KEYED

Ladislav Michl ladis at linux-mips.org
Thu Jun 30 09:56:40 CEST 2005

On Wed, Jun 29, 2005 at 06:24:40PM -0400, Dave Ellis wrote:
> The current implementation of CONFIG_SILENT_CONSOLE needs
> CFG_DEVICE_NULLDEV. I suppose a check could be added to 
> flag the error at build time if CFG_DEVICE_NULLDEV is not 
> defined.

GD_FLG_SILENT flag is checked on every output to console, nulldev device
seems redundant to me.

> In abortboot the "silent" operation is suspended by setting
> the console back to serial so you can use the console to 
> abort the boot. If the boot is aborted GD_FLG_SILENT is 
> cleared, and the serial console works. If the boot is not 
> aborted the console is set back to "nulldev" and the boot 
> continues silently.

Indeed, console is set back to serial, but it doesn't help you to see
any output. I would assume you should see at least something like
"Enter password - autoboot in n seconds"

> You can boot silently (if "silent" is set), you can 
> decide to see the output (by removing "silent" from the 
> environment) and in either case if you abort the boot 
> the console works. Isn't that exactly what the feature 
> should do?

Yes, that's what I'd expect. But is it done somehow complicated way.
Again, why there is nulldev device when GD_FLG_SILENT is checked on every
console output? Is CONFIG_AUTOBOOT_PROMPT supposed to be displayed even
with "silent" console? Would it break any user setup if I remove


More information about the U-Boot mailing list