[RFC] Generic access to firmware environment variables

[RFC] Generic access to firmware environment variables

[Jan-Benedict Glaw]

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Hi!

I've developed a driver to access environment variables on Alpha
computers from userspace through procfs some time ago. These
days, I updated the driver. While doing this, I also looked
at other architectures; some of them also do have some kind
of environment variables in firmware:

	Alphas			-	SRM firmware
	SGI Workstations	-	ARCS firmware
	MIPS/ITE-Boards		-	PMON
	m68k/MAC		-	?? (info is placed into a
					"bootinfo" struct)
	IA64			-	(_seems_ to know about
					environment...)

They all access environment variables either by name, or by an
internally handles number. For Alpha, I've (now) implemented both,
access by name (if variable name is known/described) and access by
generic number.

I think it would be useful to have something like this for other
architectures as well. So I'm currently thinking about implementing a
base driver (like parport does) and additional modules to implement
machine/architecture specific access methode (like parport_pc).

It's easy to code, so what do you think of this?

MfG, JBG

-- 
Jan-Benedict Glaw   .   jbglaw@lug-owl.de   .   +49-172-7608481
	 -- New APT-Proxy written in shell script --
	   http://lug-owl.de/~jbglaw/software/ap2/

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Re: [RFC] Generic access to firmware environment variables

[David Mosberger]

>>>>> On Wed, 10 Apr 2002 20:42:31 +0200, Jan-Benedict Glaw <jbglaw@lug-owl.de> said:

  Jan-Benedict> Hi!  I've developed a driver to access environment
  Jan-Benedict> variables on Alpha computers from userspace through
  Jan-Benedict> procfs some time ago. These days, I updated the
  Jan-Benedict> driver. While doing this, I also looked at other
  Jan-Benedict> architectures; some of them also do have some kind of
  Jan-Benedict> environment variables in firmware:

  Jan-Benedict> 	Alphas - SRM firmware SGI Workstations - ARCS
  Jan-Benedict> firmware MIPS/ITE-Boards - PMON m68k/MAC - ?? (info is
  Jan-Benedict> placed into a "bootinfo" struct) IA64 - (_seems_ to
  Jan-Benedict> know about environment...)

  Jan-Benedict> They all access environment variables either by name,
  Jan-Benedict> or by an internally handles number. For Alpha, I've
  Jan-Benedict> (now) implemented both, access by name (if variable
  Jan-Benedict> name is known/described) and access by generic number.

  Jan-Benedict> I think it would be useful to have something like this
  Jan-Benedict> for other architectures as well. So I'm currently
  Jan-Benedict> thinking about implementing a base driver (like
  Jan-Benedict> parport does) and additional modules to implement
  Jan-Benedict> machine/architecture specific access methode (like
  Jan-Benedict> parport_pc).

  Jan-Benedict> It's easy to code, so what do you think of this?

On EFI platforms, there is /proc/efi/vars.  The module was written by
Matt Domsch <Matt_Domsch@Dell.com>.  EFI is used on ia64 and x86
servers.  Note that EFI variables can contain arbitrary binary data,
not just text strings.

	--david