[ECOS] Vr4131 porting issues

Jurica Baricevic jura@INTESIS.hr
Thu Mar 20 10:52:00 GMT 2003

Nick Garnett wrote:


> Yes. eCos and RedBoot continue to run in 32 bit mode, but we context
> switch the whole 64 bit machine state. This was originally as 
> a result of
> some bugs in the toolchain: the -mgp32 wasn't being passed on to the
> assembler, so it still thought it was building for 64 bits and
> generated some 64 bit instructions. 

Ok. Thanks on clarification.

> > Do you maybe have some idea what could be 64/32 bit architecture
> > issues in eCos?
> If I knew that I would fix them :-)
> The main problem areas are in code that manipulates addresses and
> data. We use the CYG_ADDRESS and CYG_ADDRWORD types for this, but
> these are currently defined as 32 bit values for all targets. Moving
> them to 64 bits might introduce size and alignment issues in a number
> of data structures. Also, some imported code, like the BSD stack, may
> not be 64 bit clean.

Huh. Now I am more convinced that we should stick to the -mgp32. At least
in this first debugging phase.


> It is, we were slowly moving to a more generic solution for this issue
> using the __mips64 macro and the
> CYGINT_HAL_MIPS_STUB_REPRESENT_32BIT_AS_64BIT option. But we haven't
> quite got there yet.

Thanks. I understand it now.


> > [gdb-session start]
> [snip unhappy gdb]
> > [gdb-session end]
> > 
> > I don't know is it normal, but at least - it gets connected 
> at the end.
> >
> That's not right at all, it should connect smoothly. Does this still
> happen now that you are using the mipsisa32-elf toolchain?

Hm. I haven't monitored it carefully (debug remote) yet, but if I remember
connection time was also slower than I'd expect.
Anyway, what's more interesting - connection over TCP/IP seems fine. 
Maybe our serial driver is too blame.

Thank you for your help,

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