[U-Boot-Users] Re: FT u-boot shim

[Pantelis Antoniou]

On Friday 28 April 2006 10:43, Wolfgang Denk wrote:
> In message <200604281034.26439.pantelis at embeddedalley.com> you wrote:
> >
> > You're going to carry around all the FT node building code & then patch an
> > external binary blob? Or are you going to poke at hardcoded positions in 
> > the blob?
> 
> I think that binary patching of pre-defined addresses is a bad  thing
> to do, as it would soon cause more trouble and incompatibilities than
> we have right now. So the only remaining option is ...
> 
> > And that with an extra binary blob that you have to carry around, at yet
> > another danger of screwing up. How many posts in the list we're going to
> > get from users that are trying to boot with a blob for their eval board,
> > or worse "something they found in the internet"?
> 
> How many messages do we get today from user who misconfigured their system?
> 

Too many. If there's a way to screw up, users will tend to find it.
It's better to not have *any* way to screw up.

> If the kernel make rules create a single file  (a  multi-file  imagew
> with  the  kernel and the dts) then I don;t see much changes from the
> user's point of view.
> 
> > IMHO all this talk about having shims is bunk. It is trivial for the running
> > kernel to detect that a valid BLOB was passed by the bootloader. It can then
> > proceed with using a preset compiled in tree for use with non OF firmware.
> 
> So you vote for keeping duplicated versions of the dts both in U-Boot
> and in Linux?
> 

I vote for having it in u-boot only. The linux blob will be present only
for kernels with a requirement to boot on non-OF firmware.

> > But the bootloader should pass & generate the tree, if the board maintainer
> > is willing to pay the cost. 
> 
> And what is your suggestion if he is not willing to do that?
> 

Pay the cost in linux kernel size, for the Linux included blob size.
Or use an earlier version of the kernel, with all that this entails.

> Best regards,
> 
> Wolfgang Denk
> 

Regards

Pantelis