L4Linux stub drivers & L4 drivers

Alexander Valitov valitov79 at mail.ru
Fri Feb 6 17:05:56 CET 2009

Hi Adam,

Thank you for prompt answer.

I think I have found all L4Linux configuration options related to my task in
the following menuconfig’s menu:

L4Linux configuration -> Stub drivers ->

Here they are (I put corresponding variable in parentheses):

[*] Use the rtc server (L4_EXTERNAL_RTC)
[ ] Block driver for the generic_blk interface (L4_BLK_DRV)
[ ] Block driver for the persistent dataspace interface (L4_PDSPBLK_DRV)
[*] Framebuffer driver for l4con and DOpE (input/output) (L4_FB_DRIVER)
[ ]   Support for the X Window System driver (L4_FB_DRIVER_XF86IF)
[ ] Network driver for ORe (L4_ORE_DRV)
[*] Pseudo serial driver for console (L4_SERIAL)
[*]   Serial console support (L4_SERIAL_CONSOLE)
[ ]   Cons system support (L4_CONS)

Meaning of some of these options is clear for me and some of them isn’t. If
I’m right:

1. L4_EXTERNAL_RTC option forces L4Linux to use rtc module instead of direct
access to timer hardware.
2. As you wrote L4_FB_DRIVER compiles in l4fb module into L4Linux, so it
could be used by dope or con server.
3. L4_ORE_DRV adds stub network driver to L4Linux which uses ore server for
actual access to NIC.

Other isn’t really clear:

1. Help in menuconfig says 
	L4_SERIAL : "Serial type driver used for console".
	L4_SERIAL_CONSOLE : "you will be able to use the pseudo serial interface as
a system console"

I can’t get the difference between L4_SERIAL and L4_SERIAL_CONSOLE options.
Maybe L4_SERIAL is pseudo COM port driver and L4_SERIAL_CONSOLE is module
for system console (I mean ttyLv0). Am I right here?

2. Another confusing thing is that Wiki says console=ttyLv0 options is to
use 'l4ser' driver for console. But I don’t load such a module (l4ser) and
'console=ttyLv0' option works. What is 'l4ser'? Is it L4 server? If it's not
who controls COM port hardware? Is it done by L4 kernel?

3. You've mentioned "block stub without a real L4 driver". Is it L4_BLK_DRV?
Do you have plans to implement the L4 driver?

4. Unfortunately, menuconfig help isn't really comprehensible for me. Could
you please explain, in short, what is L4_CONS?



Best Regards,
 Alexander Valitov

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