H. Peter Anvin wrote:
> >When you imply it's stupid to think anyone will ever have a console on an
> >embedded system (because we all know the embedded world is far more
> >uniform than crazy diverse things like the desktop space), which of these
> >are _you_ referring to?
>
> I'm talking about the virtual console stuff, which is *not* inherently
> tied to VGA.
>
> The issue is whether it makes sense to have virtual console capability
> on a device which is so constrained that you want a *subset* of the
> functionality in place.
The uClinux devices I ship do have that. System console is the serial
port on a board header. But field engineers are instructed to plug in
a USB keyboard and Alt-F2 to get a diagnostic screen (we call it a
"shell" ;-). Occasionally even customers with specific requirements
get to use that.
We had to patch the kernel to get the combination of virtual terminal
capability on a framebuffer, but system console messages not to the
framebuffer. The uClinux (2.4.x) disables system console on a virtual
terminal, but due to some confusion(*), it has the side effect that
you can't attach a VT to a framebuffer at all. Several howtos provide
a "con2fb" program which didn't work with uClinux. We had to fix that.
(*) - the word "console" is used for four different concepts in the
kernel, sometimes in the same code, and it seems to have confused
someone.(**) In the following, CONFIG_VT_CONSOLE should not control
take_over_console(); the two "console" are not the same concept:
#ifdef CONFIG_VT_CONSOLE
take_over_console(&fb_con, first_fb_vc, last_fb_vc, fbcon_is_default);
#endif
(**) So I suggest using "virtual terminal" consistently in the code,
and when talking about them, would be an improvement.
-- Jamie
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