Re: ARM Simulator Bug?

[Richard Earnshaw <rearnsha@arm.com>]

> Hi Richard,
> 
> >Does "arm-elf-objdump -xd exe-file" display something sensible?
> 
> When I compared the working to non-working output, the only difference was in
> the private flags:
> 
> Working:
> private flags = 6: [interworking enabled] [APCS-32] [FPA float format] [has
> entry point]
> 
> Broken:
> private flags = 4: [interworking enabled] [APCS-32] [FPA float format]
> 
> It seems that it cannot find the entry point. Even though it is defined as always
> being 0x00.
> 

By only difference, I assume you mean, "other than that things are moved 
down by 32Kbytes".

Generic ELF says that an image has an entry point if (and only if) e_entry 
in the ELF header is not zero.  That's not particularly helpful on 
bare-metal ARM systems where we want an entry point at zero; so that would 
explain the difference here.  It's just possible that that is confusing 
gdb into transferring control to the wrong place, but I suspect not.

The sad thing about all this is that all the required tracing ability *is* 
built into the assembler (rdi_log). But when Cygnus integrated the 
simulator into GDB they bypassed all the code that manages that (in 
armrdi.c) and used a custom interface (wrapper.c).  So while it's all 
there, you can't get at it :-(

R.