Re: [RFC PATCH 21/23] powerpc64 is not necessarily BigEndian anymore! :)

[Ram Pai]

On Tue, Apr 01, 2014 at 10:22:10PM +0200, Vladimir 'φ-coder/phcoder' Serbinenko 
wrote:
> 
> > 
> > For the sake of bisectability this really should be moved earlier;
> > otherwise at least patch "fix parameter to firmware calls" would
> > be wrong.
> > 
> Even bigger problem is whether we want to run in LE mode at all. From
> what I understand (correct if I'm wrong) firmware calls remain
> big-endian and you need to switch back and forth between LE and BE when
> doing firmware calls.

Yes. firmware runs in 32bit BE mode. And there is a constant switch from
64bit LE to 32bit BE and vice-versa for each firmware call.

> doing firmware calls. Byteswapping for the purpose of firmware calls is
> to be avoided as bugs are easy to slip through (in fact the
> byte-swapping isn't complete in proposed patches.
> (correct me if I'm wrong) 

Is that true? maybe you are right. I might have missed something.
However please hint me what i have missed. I will look into some
other arch code that support the same ieee platform.


> these new patches cover a subset of already
> supported machines and don't add any user-visible feature and no new
> kernel type (LE kernel can be loaded from BE GRUB).
> Cross-compiling to BE from LE is easy (TARGET_CFLAGS=-EL).

Well. that is the issue.  Various distros have varied support for
cross-compilation (multi-arch support). If the distro does not 
have 32bit BE libraries natively installed (out-of-the-box), they
wont be able to generate a 32bit BE grub loader. These set of patches
overcomes the deficiency by generating a working native executable 
on LE systems.

> So it looks like this patch series adds a new high-maintenance-cost port
> covering only already supported machines and already supportred features.

It does add maintainence; I agree. But than it does overcome some
deficiences aswell.


Thanks for your comments. And sorry for the delay. I had not seen this
email, since i was not on copy. I will watch the mailing list regularly.
RP




> 



> _______________________________________________
> Grub-devel mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/grub-devel


-- 
Ram Pai