Re: Setting up crt0 and libs for arm-unknown-coff

["Scott C. Karlin" <scott at CS dot Princeton dot EDU>]

Richard Earnshaw writes:
> 
> > Thank you again for another helpful response.  The board I am using has
> > a loader pulls a coff image into memory and runs it.  The code I will
> > write will completely take control of the processor.  To make a clean
> > interface with newlib, it sounds like I should write my own SWI handler.
> > This way I won't need to make changes to newlib.
> 
> Sounds like the best way to do it; at most you may want to map the 
> particular SWI numbers onto your own preferred system call numbers, but 
> even that might be best avoided.
> 
> > 
> > The files in newlib/libc/sys/arm seem to implement the "user" side
> > of the interface.  Before I write my own, is there source available
> > which implements the "OS" side?  Is there a published interface
> > document for this?
> 
> It depends on the board that you have.  If I recall correctly, you said it 
> was an Intel board, so there is a fair chance that it is running something 
> based on Angel (our debug monitor).  You will have to contact Intel (or 
> your supplier) to find out what development kits available that support 
> your board at that level (or you could look at some of the various 
> RTOSs/kernels that are available).

The board (an IXP1200 evaluation board) has a jumper which allows
you to choose either Angel or VxWorks support from the flash ROM.
Since we are porting our own research-OS to this board, it doesn't
really make sense to use either Angel or VxWorks.  We are using
the VxWorks boot loader only to pull a coff executable over an
ethernet port.  (We chose the VxWorks boot loader over the Angel
boot loader because it was text-based.)  This executable will
take over the machine.  Since we have total control over the SWI
handler, we can make it match whatever newlib uses as its default.
So now, it seems, that I am in search of the OS/User interface
specification the ARM newlib developers used.

-Scott


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