Re: [uCsimm] Kernel module support

From: Donald J Dionne (jdionne@ns1.rt-control.com)
Date: Thu Jan 06 2000 - 14:43:04 EST


> Hi All,
>
> I've been looking into the possibility of porting RTLv1 to uClinux. One
> of the first requirements is that you need kernel module support (as the
> RT apps are loaded as kernel modules). Looking through the old mailing

This is not actually a requirement for a uClinux based RTL. I've looked
at the RTLv1 and v2 code in the past few days and there are only a few
calls into the RT layer. What we need to do is arrange for those functions
to be called through the system call interface (or perhaps another trap
number). Since there is no MMU, things are a little easier since the
RT kernel or Linux can make callbacks directly into "user space".
RTL programs will be just that, programs not modules.

Still, RTL is not going to be a trivial port.

> list stuff I see that kernel modules aren't supported. If you try to
> build the kernel with this option you get:

Supporting modules is a lot of work. I can't see any show stoppers however.
insmod is where most of the work is. The error below is a chunk of code
that can actually just come right out, without an MMU we don't need to
bother remaping, just link it all up in place.

Jeff.

>
> make[2]: Entering directory `/opt/uClinux/linux-rt/kernel'
> m68k-coff-gcc -D__KERNEL__ -I/opt/uClinux/linux-rt/include -Wall
> -Wstrict-prototypes -O2 -fomit-frame-pointer -fno-strength-reduce
> -D__RT__ -pipe -DNO_MM -DNO_FPU -m68000 -D__COFF__ -DMAGIC_ROM_PTR
> -DNO_FORGET -DUTS_SYSNAME='"uClinux"' -c -o ksyms.o ksyms.c
> ksyms.c:140: `remap_page_range' undeclared here (not in a function)
> ksyms.c:140: initializer element for `symbol_table.symbol[16].addr' is
> not constant
> make[2]: *** [ksyms.o] Error 1
> make[2]: Leaving directory `/opt/uClinux/linux-rt/kernel'
> make[1]: *** [first_rule] Error 2
> make[1]: Leaving directory `/opt/uClinux/linux-rt/kernel'
>
> Does anyone have any ideas what would be needed to add kernel module
> support (or even whether it is a practical idea).
>
> Regards, Stuart
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>

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