Re: Comparing Bill and Karim's cross-compile scripts. Updating Bill'sto gcc 3.2.3.

[Bill Gatliff <bgat at billgatliff dot com>]

Karim et al:

> Lately, though, I was thinking about making a list of all available
> scripts, and I came up with this (which, of course, includes Bill's
> script):
> http://www.embeddedtux.org/pipermail/etux/2003-May/000018.html

That's a nice resource.

> The copying of asm-generic was added following a recommendation by Russell
> King, maintainer of the Linux ARM port.

I can confirm that copying of asm-generic is required for MIPS targets 
as well.

> The way I see it, and the way I tried to word it in the book, is that this
> is really just good practice, because if you don't use CROSS_COMPILE=
> all the time, you end up forgetting to use it when you need to. You can
> skip it if you know what you're doing, as I suggest in the book.

Ditto.  In my classroom experience, I've found it less error-prone to 
teach everyone to specify CROSS_COMPILE as well.  Over time, as their 
skills improve, they "discover" how to fix it for themselves.  Provides 
a nice opportunity for a "teaching moment".

> I haven't really found this to be a show-stopper in the cases I've
> tested.

I think this is probably a holdover from my experiences with older 
versions of glibc.

> Actually I found this the hard way. I used to put --prefix=$PREFIX,
> just like most cross-setup tool instructions out there do,
> but then I'd have to set LD_LIBRARY_PATH on the target, which sounded
> odd. And sure enough, a few reviewers pointed out during the review that
> a correctly build toolchain shouldn't need LD_LIBRARY_PATH=/lib. So I
> scratched my head a little more, RTFM'ed, tried a couple of things, and
> found that /usr is the only proper setting for --prefix here.
>
> As for "--prefix=/usr" being a special case for Linux, this is straight
> out of the GLIBC build instructions. In the "Specific advice for Linux
> systems" section of the INSTALL file, it says:
> "   Linux expects some components of the libc installation to be in
> `/lib' and some in `/usr/lib'.  This is handled automatically if you
> configure glibc with `--prefix=/usr'.  If you set some other prefix or
> allow it to default to `/usr/local', then all the components are
> installed there."

That's pretty much how I got to where I am now, trial and error.  :^(

Those experiences haven't found their way back into the 
build-crossgcc.sh script, mostly because that script was originally 
intended for non-linux targets.  I was under the impression at the time 
that crossgcc was mainly about non-linux targets, and that users of the 
script wouldn't want to see the additional complexity required to build 
a linux toolchain.  Perhaps times have changed?

> I have tried to keep the instructions identical in as much as possible
> across all archs. There are some archs which require a few tricks,
> that's true. In as far as a comparison is made between instructions,
> however, I do cover all the *Linux* arch-specific tricks I can see in
> Bill's script. Most notably, the -Dinhibit_libc hack for ARM is covered
> in table 4-2 on p.111.

It's unfortunate that the instructions aren't identical across all 
architectures.  Maybe someday.


b.g.
--
Bill Gatliff
bgat@billgatliff.com


------
Want more information?  See the CrossGCC FAQ, http://www.objsw.com/CrossGCC/
Want to unsubscribe? Send a note to crossgcc-unsubscribe@sources.redhat.com