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Re: [uClinux-dev] why no-mmu cannot support binfmt_aout.c
- From: Jamie Lokier <jamie at shareable dot org>
- To: loody <miloody at gmail dot com>
- Cc: uClinux development list <uclinux-dev at uclinux dot org>, gcc-help <gcc-help at gcc dot gnu dot org>, binutils at sourceware dot org
- Date: Thu, 29 Jan 2009 10:56:14 +0000
- Subject: Re: [uClinux-dev] why no-mmu cannot support binfmt_aout.c
- References: <20090126235125.GC9296@shareable.org> <3a665c760901270902r582c60dfm2668a30c754aaf17@mail.gmail.com> <20090127183339.GA23412@shareable.org> <3a665c760901281016i562c8f6h36e77d72946bc704@mail.gmail.com> <4980EE0E.9040307@snapgear.com> <3a665c760901281600q19a5d0d2n4c4bb321cdbfba6c@mail.gmail.com> <4980F5C8.3040202@snapgear.com> <3a665c760901282207g5e203ef0rfbd51a1c2c9a80a9@mail.gmail.com> <20090129061215.GD19270@shareable.org> <3a665c760901282308t52ed3243j460dc2eb2f43671b@mail.gmail.com>
loody wrote:
> 2009/1/29 Jamie Lokier <jamie@shareable.org>:
> > loody wrote:
> >> e1a0e00f mov lr, pc
> >> e12fff13 bx r3
>
> Actually my cpu get exception when executing this instruction not bx r3.
> But lr is the destination for cpu to write, I have checked the arm
> reference and it doesn't say any cautions when the destination is lr.
You're right, that doesn't make sense to me either.
> > "bx" is not available on all ARMs, and will fault when you don't have
> > it. That's why it's necessary to build everything with the right GCC
> > options.
>
> There are bx instructions generated when I use arm-linux-2006.
>
> BTW, can I take off the Thumb support in my compiler options?
> Thumb is only used for decreasing the density of source code and so
> far I just want my kernel say hello to me.
At this point, you may want to subscribe to the linux-arm mailing
list, and ask the question again there :-)
http://lists.arm.linux.org.uk/mailman/listinfo/linux-arm
-- Jamie