[syslinux] change SERIAL baudrate as-needed?

[Steve Rikli]

On Mon, Apr 27, 2015 at 06:19:19AM -0400, Gene Cumm wrote:
> 
> Why not just automatically set SERIAL once to the right speed?  Can
> you distinguish between old 9600 clients and new 115200 clients by
> system UUID, MAC address or IP prefix?  If not, perhaps an if*.c32
> moddule (existing or custom)?  Adding UUIDs one at a time (even by
> symlink) could be very tedious for many boot clients although perhaps
> worthwhile since you're reconfiguring a terminal server (likely also
> by hand).

No, I'm not reconfiguring any terminal servers -- they are already setup
the way they need to be, whether 9600 or 115200.

I need to be able to support either speed for the forseeable future with
the same Kickstart infrastructure.  For this multi-lab and multi-system
type environment, the trick for me (as you touched on below) will likely
be figuring out how to give the right PXElinux default menu to systems
with 115200 vs. 9600 consoles.

> Your current solution would require that you boot with the terminal
> server at 9600, manually use a menu to select a new CONFIG (which
> changes to 115200), then manually change the terminal server to 115200
> and force a screen redraw.

Again, the terminal server configs are static.  But you raise the key
point -- how to set the correct initial console speed to drive the
rest of the interactive install menus?

> With this, the second menu would probably
> be better off not loaded automatically as I can't find any way to
> force menu.c32 to perform a screen redraw.  The closest to this would
> be a sleep.c32 which would be near trivial for me write and would
> sleep for 25 seconds then execute "menu-label" when called as the
> following:
> 
>     sleep.c32 25 menu-label
> 
> Changing serial rates or performing a capture of sorts (packet,
> screen, etc) are probably the only use cases I could think of for it.

I am aware of the administrative challenges of our multi-lab environment.
:-)  It's complicated by the fact that I'm not the only consumer of the
Kickstart infrastructure, though I am the maintainer.

Your point is well-taken -- i.e. it may be that the best solution will
be to have different default files for the different console speeds and
hand the right one to the clients when they start an install.  The rest
of the sub-menus could still be shared, I believe.

Thanks,
sr.