Complining with codesurgery 4.4.-43 sh2a

Complining with codesurgery 4.4.-43 sh2a

[Fabio Giovagnini]

Hi all, why I need to compile my code with -m2a -m2a-nofpu aven if sh2a 76203 
has an fpu?
If I do not use -m2a-nofpu I have error
 undefined reference to `__fpscr_values'
at linking time

Thanks




In data venerdì 19 marzo 2010 09:24:04, Magnus Damm ha scritto:
: > Hi Fabio,
> 
> On Fri, Mar 19, 2010 at 2:27 PM, Fabio Giovagnini
> 
> <fabio.giovagnini@aurion-tech.com> wrote:
> > Hi, could you tell me please how to find info about using qemu for sh2a
> > if it is possible?
> 
> QEMU did not support sh2a last time I checked. And I doubt that anyone
> added it recently.
> 
> It may however be a good idea to use QEMU to learn about initramfs and
> user space programs on a different processor or architecture.
> 
> If I were you then I'd try to get QEMU working with x86 as target.
> When you have initramfs working on x86 in QEMU then you can easily
> move over to some other target. With sh2a on real hardware with an old
> kernel version there are too many unknowns to make efficient progress.
> 
> Cheers,
> 
> / magnus
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> 

-- 
Fabio Giovagnini

Aurion s.r.l.
P.I e C.F.
00885711200
Tel. +39.051.594.78.24
Cell. +39.335.83.50.919

Re: Complining with codesurgery 4.4.-43 sh2a

[Paul Mundt]

On Fri, Mar 19, 2010 at 12:01:23PM +0100, Fabio Giovagnini wrote:
> Hi all, why I need to compile my code with -m2a -m2a-nofpu aven if sh2a 76203 
> has an fpu?
> If I do not use -m2a-nofpu I have error
>  undefined reference to `__fpscr_values'
> at linking time
> 
You should never be touching any of the Makefile build flags, they are
delicate, have rigid ordering requirements, and are mapped out the way
they are intentionally. Any time you are forced to hack up build flags
you are almost guaranteed to be doing something wrong.

Whether the CPU has an FPU or not is completely irrelevant from the
context of the kernel. The kernel does not have its own FP state, and so
can't handle having FP instructions generated by the compiler, this is
what the -nofpu inhibiting is for. Even in situations where the kernel
may wish to hand craft FP context and open code a few instructions, the
kernel is never built without -nofpu.

Re: Complining with codesurgery 4.4.-43 sh2a

[Fabio Giovagnini]

In fact I used the toolchain for building the binary file including the 
bootstrap code and the zImage of the kernel;and this told me the prolem 
beacuse in my own makefile I had -m2a only option set.

Do I have to skip the fpu when I'll build the usersapce application?


Thanks a lot Paul



In data venerdì 19 marzo 2010 12:27:35, Paul Mundt ha scritto:
: > On Fri, Mar 19, 2010 at 12:01:23PM +0100, Fabio Giovagnini wrote:
> > Hi all, why I need to compile my code with -m2a -m2a-nofpu aven if sh2a
> > 76203 has an fpu?
> > If I do not use -m2a-nofpu I have error
> >  undefined reference to `__fpscr_values'
> > at linking time
> 
> You should never be touching any of the Makefile build flags, they are
> delicate, have rigid ordering requirements, and are mapped out the way
> they are intentionally. Any time you are forced to hack up build flags
> you are almost guaranteed to be doing something wrong.
> 
> Whether the CPU has an FPU or not is completely irrelevant from the
> context of the kernel. The kernel does not have its own FP state, and so
> can't handle having FP instructions generated by the compiler, this is
> what the -nofpu inhibiting is for. Even in situations where the kernel
> may wish to hand craft FP context and open code a few instructions, the
> kernel is never built without -nofpu.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-sh" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

-- 
Fabio Giovagnini

Aurion s.r.l.
P.I e C.F.
00885711200
Tel. +39.051.594.78.24
Cell. +39.335.83.50.919