PROM variables

PROM variables

[Vincent Stehlé]

Hi all,

Is there a way to get/set PROM variables under Linux ?

I have an indigo2 with no display, and setting the variables without 
reverting to the monitor through the serial line would be very handy.

As I doubt there is currently a solution, I was thinking about 
implementing this as a /proc subdir. What do you think ?

Regards,

-- 
  Vincent Stehlé

Re: PROM variables

[Juan Quintela]

>>>>> "vincent" == Vincent Stehlé <vincent.stehle@stepmind.com> writes:

vincent> Hi all,

vincent> Is there a way to get/set PROM variables under Linux ?

vincent> I have an indigo2 with no display, and setting the variables without
vincent> reverting to the monitor through the serial line would be very handy.

vincent> As I doubt there is currently a solution, I was thinking about
vincent> implementing this as a /proc subdir. What do you think ?

You can set them through the serial console in the same way that you
can set it in the monitor?

Are you sure that you have set the prom variables to use the serial
console?

Later, Juan.

-- 
In theory, practice and theory are the same, but in practice they 
are different -- Larry McVoy

Re: PROM variables

[Guido Guenther]

Hi Vincent,
On Thu, Mar 13, 2003 at 11:04:22AM +0100, Vincent Stehlé wrote:
> Is there a way to get/set PROM variables under Linux ?
Not for IP22.

> I have an indigo2 with no display, and setting the variables without 
> reverting to the monitor through the serial line would be very handy.
If you pull out the graphics board the machine will switch to the serial
line.

> As I doubt there is currently a solution, I was thinking about 
> implementing this as a /proc subdir. What do you think ?
What about multiple files in /proc/arcs which have the PROM variables as
name and its value as contents? When doing this I'd write into the NVRAM
directly instead of using the Arcs functions, I think the necessary info
is in the IRIX headers.
Regards,
 -- Guido

Re: PROM variables

[Ladislav Michl]

On Thu, Mar 13, 2003 at 11:04:22AM +0100, Vincent Stehlé wrote:
> Hi all,
> 
> Is there a way to get/set PROM variables under Linux ?

no.

> I have an indigo2 with no display, and setting the variables without 
> reverting to the monitor through the serial line would be very handy.
> 
> As I doubt there is currently a solution, I was thinking about 
> implementing this as a /proc subdir. What do you think ?

we discussed this issue on #irc yesterday. it seems that conclusion was
implement it as ioctl on some /dev/prom (?).

	ladis

Re: PROM variables

[Ladislav Michl]

On Thu, Mar 13, 2003 at 11:26:01AM +0100, Guido Guenther wrote:
[snip]
> > As I doubt there is currently a solution, I was thinking about 
> > implementing this as a /proc subdir. What do you think ?
> What about multiple files in /proc/arcs which have the PROM variables as
> name and its value as contents? 

hmm, how would you add/remove variable?

> When doing this I'd write into the NVRAM directly instead of using the
> Arcs functions, I think the necessary info is in the IRIX headers.
> Regards,
>  -- Guido

Re: PROM variables

[Juan Quintela]

>>>>> "ladislav" == Ladislav Michl <ladis@linux-mips.org> writes:

ladislav> On Thu, Mar 13, 2003 at 11:26:01AM +0100, Guido Guenther wrote:
ladislav> [snip]
>> > As I doubt there is currently a solution, I was thinking about 
>> > implementing this as a /proc subdir. What do you think ?
>> What about multiple files in /proc/arcs which have the PROM variables as
>> name and its value as contents? 

ladislav> hmm, how would you add/remove variable?

echo "value" > new_variable_name 

??

Later, Juan.


-- 
In theory, practice and theory are the same, but in practice they 
are different -- Larry McVoy

Re: PROM variables

[Juan Quintela]

>>>>> "ladislav" == Ladislav Michl <ladis@linux-mips.org> writes:

ladislav> On Thu, Mar 13, 2003 at 11:26:01AM +0100, Guido Guenther wrote:
ladislav> [snip]
>> > As I doubt there is currently a solution, I was thinking about 
>> > implementing this as a /proc subdir. What do you think ?
>> What about multiple files in /proc/arcs which have the PROM variables as
>> name and its value as contents? 

ladislav> hmm, how would you add/remove variable?

Forgot to tell how to remove the variable in previous mail :)

rm old_variable 

should do, no need at all of ioctl crap :)

Later, Juan.



-- 
In theory, practice and theory are the same, but in practice they 
are different -- Larry McVoy

Re: PROM variables

[Vincent Stehlé]

Guido Guenther wrote:
[..]
> When doing this I'd write into the NVRAM
> directly instead of using the Arcs functions, I think the necessary info
> is in the IRIX headers.

I had a look at the ARC spec. (ARC/riscspec.pdf), and I am affraid the 
only (documented) way to access PROM env. variables are the two get/set 
functions.

In that case, the /proc approach makes sense IMHO.

Looking at hpc3 spec. and ip22-sc.c, I understand that PROM data are 
stored in the EEPROM behind the hpc3.

Maybe a reasonable approach is:

o write a new char device driver (as pc's /dev/nvram for example)
o move eeprom read/write routines from ip22-sc.c somewhere else,
   and use those routines both in ip22-sc.c and the char driver
o guess the format/offsets of the info. stored in nvram
o then write some user space app. to do the env. variable
   specific part.

In that latter case, the /proc approach makes less sense IMHO.

What do you think ? Am I missing some documentation ? Is there more in 
the IRIX headers ? (can't check right now, but I have them at home)

Regards,

--
  Vincent Stehlé