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SubjectRe: Bug in kernel - how to make big kernel bootable with GRUB (was Re: Linux 2.4.0-Test{1,2} with Grub (I think I found the answer))


On Fri, 14 Jul 2000, Khimenko Victor wrote:
>
> Huh. Patch is trivial. Really trivial. Just one problem: I do not think it'll
> be applied. Since it's TWO patches: one for kernel and one for GRUB.

Actually, the only problem with the patch is that it is not
byte-order-safe, which means that you cannot cross-compile from a
big-endian host.

I don't see any real problem in extending syssize to be 4 bytes, as the
two ne wbytes that it writes over are the "swap_dev" bytes that I don't
think anybody ever used. We might as well get rid of them. And thanks to
being little-endian, it would not change for loaders that don't know about
the new 4-byte format (the two low bytes are still the same).

So I won't apply the patch as-is, but fix it to be endian-safe and get
some input from other bootloaders (assuming they all agree that swap_dev
is a non-issue - which I think they will) and I _will_ apply it.

> Who's the bright idea was to extend maximum kernel beyond 1MB and STILL write
> only two bytes of sys_size in boot sector anyway ? And why it was done via
> buf in first place ?

I'd be careful about calling other people stupid if you don't understand
the code.

Using "buf" the way the code used it meant that people whose native
byte-order was big-endian would still be able to build images. Performance
was never a big issue here, so it works fine. It may not be pretty, but I
doubt beauty was a big issue either ;)

The field never got extended because nobody really needed it extended.
That's as simple as it can get, no?

Linus


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