Subject:
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Re: Library use in LegOS
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Tue, 27 Mar 2001 12:16:30 GMT
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Viewed:
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3736 times
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In lugnet.robotics.rcx.legos, Jakob Engblom writes:
> > Each program gets it's own copy
>
> OK.
>
> How are the calls to the kernel resolved? By the makelx program, or by some
> magical stuff in the linking.
>
> I can imagine compiling the kernel, getting a symbol table out, and then
> when compiling user programs, you use a linker DEFINE or such to tell the
> code that yes, there is such a function, at this absolute address. However,
> getting this to work automatically seems like a lot of work.
Not sure of the details, but the linker takes the .o file, and the symbol file
LegOS.lds, created during the kernel compile, and produces two files; .ds1 &
.ds2, which are then passed to makelx to produce the lx file. So it seems the
linker resolves kernel symbols, not makelx.
> > > If I would use a different compiler, with a different set of libraries for
> > > the program and the kernel, is there the potential for namn clashes?
> >
> > Hmmmm. Not sure. Wish I knew more about compiler internals...
>
> Well, if each program uses its own libraries, there is no risk. The linked
> binary from my compiler will call LegOS via some mechanism, and its own
> libraries internally in the binary. No problem.
>
> > > How much of the LegOS-gcc standard libraires come from gcc and how much • have
> > > been hacked specifically for legos?
> >
> > It's all custom written - doesn't use the standard gcc libraries at all. In
> > fact when building the cross compiler, you have to tell it to forget about
> > the standard libraries.
>
> Why is that? For the IAR compiler we are going to use, the libraries are
> completely operating-system neutral (strlen, memcpy, math libs, etc have
> nothing to do with the operating system).
I think it's mainly for size - but I wasn't involved with the early versions of
LegOS, so maybe someone else knows more...
I guess libc could also be used for the H8 but I don't know if anyones tried
this.
> Lots of questions, but I am trying what apparently nobody has tried before,
> since I only have seen gcc discussed here in the legOS forum.
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Message has 1 Reply:
 | | Re: Library use in LegOS
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| (...) of (...) For the IAR compiler, this should not a problem. The libraries are optimized for minimal size, so we can probably use the standard libraires. And give our students the benefit of a full C lib. /jakob (25 years ago, 28-Mar-01, to lugnet.robotics.rcx.legos)
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Message is in Reply To:
| | Re: Library use in LegOS
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| (...) OK. How are the calls to the kernel resolved? By the makelx program, or by some magical stuff in the linking. I can imagine compiling the kernel, getting a symbol table out, and then when compiling user programs, you use a linker DEFINE or (...) (26 years ago, 27-Mar-01, to lugnet.robotics.rcx.legos)
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