Re: [RFA] Support for GDB on SGI Irix 6.x

[Andrew Cagney <ac131313@cygnus.com>]

> This is a followup for
> 
>    http://sources.redhat.com/ml/gdb-patches/2001-05/msg00341.html
> 
> where I posted a set of patches to make GDB support n32 executables on
> SGI Irix.  Since then, David Anderson reported that, with a minor
> change in irix6.mh, GDB builds and works on SGI for him as well.
> 
> So I would like to commit these changes (reproduced below).  Any
> objections?
> 
> 
> 2001-06-04  Eli Zaretskii  <elis@is.elta.co.il>
> 
> * config/mips/tm-irix6.h: New file.
> 
> 	* config/mips/irix6.mh: New file.
> 
> 	* config/mips/irix6.mt: New file.
> 
> 	* config/mips/xm-irix6.h: New file.
> 
> 	* config/mips/nm-irix6.h: New file.
> 
> 	* mips-tdep.c (mips_gdbarch_init) <MIPS_ABI_N32>: Set up the
> 	disassembler info in tm_print_insn_info as appropriate for the N32
> 	ABI.  Force N32 ABI to be the default if the CPU is R8000 or
> 	R10000.
> 
> 	* configure.tgt (mips*-sgi-irix6*): Map to irix6.
> 
> 	* configure.host (mips*-sgi-irix6*): Ditto.
> 


No.

	Andrew

PS: For those that are wondering. Eli's code contains things like:

> +#undef  REGISTER_BYTES
> +#define REGISTER_BYTES (MIPS_NUMREGS * 8 + (NUM_REGS - MIPS_NUMREGS) * MIPS_REGSIZE)
> 

yet MIPS is ment to be multi-arch.  MIPS is actually multi-arch except 
for the register buffer and a few other things.  The MIPS register 
buffer hasn't been multi-arched because doing it would break GDB's 
remote MIPS G packet support. (Yes, this is exactly what JimB was 
refering to).

To safely fix this, I think remote.c would need to be changed so that it 
allowed:

	o	several different pre-defined G packet
		layouts for a single architecture

	o	a CLI mechanism that allows the user
		to either select a pre-defiend G packet
		format _OR_ define their own custom
		G packet format.

The latter is the key requirement.  When the MIPS registers get 
multi-arched I think the process is 100% guarenteed to break support for 
GDB talking to some obscure remote MIPS target.  Adding support for G 
packet CLI specs at lets users of such targets work around the problem.

	Andrew