Re: Questions on crosstool

[Lennert Buytenhek <buytenh at wantstofly dot org>]

On Sun, Aug 08, 2004 at 09:34:18PM -0700, Dan Kegel wrote:

> >5. I have a customized (support for new xscale hardware)
> >  2.4.21 kernel source code. This source code has no problem
> >  with gcc 3.2. I set the path to the toolchain's bin directory
> >  and compiled. I had three major problems during compile
> >  time and did he following changes:
> >
> > a. Removed the flags -Wa,-mno-fpu
> 
> Hmm.  I'm not sure about that, but I wouldn't know.

With Robert's softfloat patch, the assembler already gets passed
-mfpu=softvfp (twice, even, hmmmm) and then if you add -Wa,-mno-fpu
gas says:
	Assembler messages:
	Error: use of old and new-style options to set FPU type

But I can imagine that we'd want to override this for the kernel --
in the kernel, we wouldn't want floating point to be used at all.
Hmmmm.


> > Should I have let crosstools not download linux code from
> >kernel.org and instead modify it to use the kernel code I
> >have ?
> 
> Sure - just drop a kernel tarball in the download directory,
> and crosstool will use that instead of downloading.
> You might also want to use your own kernel .config file
> instead of the stock (or nonexistent) one crosstool uses.
> - Dan

I've had troubles with using 2.4 kernel header to generate an ARM
toolchain.  unistd.h defines __NR_waitpid, but the 2.4 kernel I was
using at the time didn't have sys_waitpid for ARM (Did there ever
exist a sys_waitpid for ARM?), so glibc ended up calling a system
call that simply wasn't there and failing in a lot of strange cases.

In 2.6, __NR_waitpid has been removed, so building glibc with 2.6
kernel headers no longer makes it call that syscall -- it then uses
an emulation via wait() instead, IIRC.


--L

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