Re: [Etherboot-users] Getting the original BOOTP values in userspace after boot

[Donald J C. <dj...@ci...>]

Mark Atwood wrote:
> 
> I'm using Etherboot to book Linux 2.4. Is there a way for
> a userspace program get a list of all the BOOTP/DHCP tags & values
> that booted the image?

As Ken said, first32.c can copy things into the parameter string and
it will show up in /proc/cmdline.  I believe there is 512 bytes of
space to work with.  I rearranged things and got 2k, which is all the
kernel supports (at least last time I checked.)  I am passing a bunch
of things to the application level
that way.

I have changed the code too much for you to use it directly, but I can
share a snippet that adds strings to /proc/cmdline to use as an example.
You'll have to fit this into first32.c.  Remember, the first32.c that
I am using is quite different from the distributed first32.c, but this
code should be pretty close to usable.  YMMV.


    params = ( char * )seg[ S_PARAMS ]->p_paddr;

    /* p is insertion point for new parameters */
    p = params + strlen( params );
    *p++ = ' ';

    /* Copy image file name to params */
    {
        /* NOTE: params is not checked for enough space */
        unsigned char s[ 128 ];
        sprintf( s, "fwvers=%d.%s%d platform=xyz img=",
                 eb->major, eb->minor < 10 ? "0" : "", eb->minor );
        for ( i = 0; i < strlen( s ); i++ )
            *p++ = s[ i ];
        for ( i = 0; i < strlen( bp->bp_file ); i++ )
            *p++ = bp->bp_file[ i ];
        *p++ = ' '; /* space, not null, since another option follows */
    }

    {
        /* NOTE: params is not checked for enough space */
        unsigned char s[ ] = "cfg=";
        for ( i = 0; i < strlen( s ); i++ )
            *p++ = s[ i ];

        /* Find config file name and copy it to params */
        q = gettag(RFC1533_VENDOR_SPECIFIC);
        if (( q[ 0 ] != 0 ) && ( q[ 1 ] == 67 ))
        {
            i = q[ 2 ];
            q += 3;
            while ( i-- > 0 )
                *p++ = *q++;
        }
        else
        {
            unsigned char s2[ ] = ".cfg";
            for ( i = 0; i < strlen( bp->bp_file ); i++ )
                *p++ = bp->bp_file[ i ];
            for ( i = 0; i < strlen( s2 ); i++ )
                *p++ = s2[ i ];
        }
        *p++ = '\0';
    }

    /* Move parameters to end of parameter area,
       tail first to avoid overwriting */
    q = params + PARAMSIZE;

    /* At least 1 byte is copied, the NUL */
    do {
        *--q = *--p;
    } while ( p != params );
    ip = q;
    op = params;
    process_params( );
    if ( verbose )
        printf( "Parameters: %s\n", params );


--
Don Christensen    Senior Software Development Engineer
  dj...@ci...    MMABU - Mid-Market Access Business Unit
  Cisco Systems    ComLOB - Commercial Line of Business
   San Jose, CA    "So much relies on the course that you take
                   The fool and the wise man both burn at the stake"