Re: RFA: handle missing fpregs

[Jason Thorpe <thorpej@wasabisystems.com>]

On May 10, 2004, at 3:15 PM, Jim Blandy wrote:

Thanks for looking at this.

How about changing the comment to this:

  /* FIXME: jimb/2004-05-05: Some PPC variants don't have floating
     point registers.  Traditionally, GDB's register set has still
     listed the floating point registers for such machines, so this
     code is harmless.  However, the new E500 port actually omits the
     floating point registers entirely from the register set --- they
     don't even have register numbers assigned to them.
     It's not clear to me how best to update this code, so this assert
     will alert the first person to encounter the NetBSD/E500
     combination to the problem.  */
Ah, this clarifies the situation greatly.  I didn't realize that we 
were in E500 land with this change.

How is the change to the code itself?  The present code, if run when
the current architecture is the E500, will just inappropriate numbers
for the floating-point registers and hit the assert in
regcache_raw_supply, if you're lucky.  So the change is an improvement
over the current state of affairs.
If I am to understand correctly, the assert won't trip on e.g. 405 or 
440... if that is true (i.e. does not break NetBSD FPU-less PowerPC 
support that currently works), then it's OK with me.

Thanks!

        -- Jason R. Thorpe <thorpej@wasabisystems.com>

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From jimb@redhat.com Mon May 10 22:45:00 2004
From: Jim Blandy <jimb@redhat.com>
To: gdb-patches@sources.redhat.com
Subject: RFA: remove meaningless code in ppc-bdm.c
Date: Mon, 10 May 2004 22:45:00 -0000
Message-id: <vt2pt9bvr42.fsf@zenia.home>
X-SW-Source: 2004-05/msg00314.html
Content-length: 2477

I was going through this trying to keep it up to date with the
register numbering changes I was making, but then I realized it was
complete jibberish.  First, the register contents are binary data; you
can't strcat them.  Second, you can't strcat them into a fixed-size
buffer that is already filled with non-zero bytes.

2004-05-10  Jim Blandy  <jimb@redhat.com>

	* ppc-bdm.c (bdm_ppc_fetch_registers): Replace utterly broken code
	with a call to internal_error.

Index: gdb/ppc-bdm.c
===================================================================
RCS file: /cvs/src/src/gdb/ppc-bdm.c,v
retrieving revision 1.22
diff -c -p -r1.22 ppc-bdm.c
*** gdb/ppc-bdm.c	10 May 2004 18:58:44 -0000	1.22
--- gdb/ppc-bdm.c	10 May 2004 22:43:08 -0000
*************** bdm_ppc_fetch_registers (int regno)
*** 155,174 ****
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
    int i;
!   unsigned char *regs, *beginregs, *endregs, *almostregs;
!   unsigned char midregs[32];
!   unsigned char mqreg[1];
    int first_regno, last_regno;
    int first_bdm_regno, last_bdm_regno;
!   int reglen, beginreglen, endreglen;
! 
! #if 1
!   for (i = 0; i < ppc_num_fprs; i++)
!     {
!       midregs[i] = -1;
!     }
!   mqreg[0] = -1;
! #endif
  
    if (regno == -1)
      {
--- 155,164 ----
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
    int i;
!   unsigned char *regs;
    int first_regno, last_regno;
    int first_bdm_regno, last_bdm_regno;
!   int reglen;
  
    if (regno == -1)
      {
*************** bdm_ppc_fetch_registers (int regno)
*** 217,236 ****
  	}
      }
    else
!     /* want all regs */
!     {
! /*      printf("Asking for registers %d to %d\n", first_regno, last_regno); */
!       beginregs = ocd_read_bdm_registers (first_bdm_regno,
! 					  tdep->ppc_fp0_regnum - 1,
!                                           &beginreglen);
!       endregs
!         = (strcat (midregs,
!                    ocd_read_bdm_registers (tdep->ppc_fp0_regnum + ppc_num_fprs,
!                                            last_bdm_regno - 1, &endreglen)));
!       almostregs = (strcat (beginregs, endregs));
!       regs = (strcat (almostregs, mqreg));
!       reglen = beginreglen + 32 + endreglen + 1;
!     }
  
  #endif
  #if 0
--- 207,215 ----
  	}
      }
    else
!     internal_error (__FILE__, __LINE__,
!                     "ppc_bdm_fetch_registers: "
!                     "'all registers' case not implemented");
  
  #endif
  #if 0