Re: [LinuxBIOS] patch: extending LAR, and removing elf from linuxbios (it is not needed)

[Stefan Reinauer]

* ron minnich  [070828 18:11]:
> On 8/28/07, Carl-Daniel Hailfinger  wrote:
> > OK, so I was unclear. The idea was to number the payloads as well, not
> > only the segments.
>
> Let's hold off on that, it will require a lot of changes, and it is
> not really what we planned. We have normal and fallback; there is
> really nothing in the design for normal0, normal1, etc.

We don't even have normal and fallback at the moment. And I doubt it
will come back, except artificially.

I think we have two choices:

* either fallback becomes _really_ stupid and just tries to load a
  payload via ymodem

* or fallback/normal is linuxbios and has nothing to do with the
  payload. So N linuxbios images (N=2.. normal and payload) will be able
  to load M (might be 2, but no requirement) payloads.
> > We simply could reserve some space at the end of the header and use that
> > for future extensions without having to change a version number. Only if
> > the extension needs changes in earlier fields of the struct we would
> > have to change the MAGIC.
>
> It gets messy. We'd have to implement version # management in
> lib/lar.c, and I think that's a different coding discussion which I
> would rather not include in this patch.

The simplest version management you could think of:

if (lar_version > my_version) {
        printf("Your image is too new. upgrade lar utility\n");
        exit(1);
}

if (lar_version > my_version) {
        printf("Your image is too old. downgrade lar utility\n");
        exit(1);
}

or even

if (lar_version != my_version) {
        printf("Your image version and lar utility version do not match. Change either\n");
        exit(1);
}

Anything beyound the above is a waste of precious time imho.
Let's not do migration paths for pre-pre-pre-pre-pre-production
software.

Stefan