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From: Richard Earnshaw <rearnsha@arm.com>
To: gdb-patches@cygnus.com
Cc: richard.earnshaw@arm.com
Subject: Re: support for ARM GNU/Linux
Date: Wed, 14 Apr 1999 03:36:00 -0000	[thread overview]
Message-ID: <199904140952.KAA25068@sun52.NIS.cambridge> (raw)
In-Reply-To: <37142B16.B43B5200@cygnus.com>

ac131313@cygnus.com said:
> I'm slightly curious about what is going on with all these different
> breakpoints (I should hasten to point out that I'm _not_ the ARM
> expert/maintainer :-).  Stan Shebs recently commited the change:

> 	1999-03-02  Stan Shebs  <shebs@andros.cygnus.com>

> 	From Gary Thomas  <gthomas@cygnus.co.uk>:
> 	* arm-tdep.c (ARM_LE_BREAKPOINT, ARM_BE_BREAKPOINT,
> 	THUMB_LE_BREAKPOINT, THUMB_BE_BREAKPOINT): Use illegal instruction
> 	instead of SWI 24.
> 	* config/arm/tm-arm.h (CALL_DUMMY): Ditto.
> 	(IN_SIGTRAMP): Define. 


A bit of history.  SWI 24 was the breakpoint swi in RISC iX, which the 
kernel understood (in some way).  I don't know if it was necessary to use 
exactly that SWI if you were using gdb or if the same effect could be 
achieved with other illegal instructions.

A side-note, before ARM Architecture v4 many "undefined" instruction 
formats aren't guaranteed to take the undefined instruction trap.  Also 
note that, in this respect, the ARM7TDMI is NOT fully ARM v4 compliant.

I don't know if anyone cares about RISC iX support any more (though gcc 
still supports it).

Richard.


WARNING: multiple messages have this Message-ID
From: Richard Earnshaw <rearnsha@arm.com>
To: gdb-patches@cygnus.com
Cc: richard.earnshaw@arm.com
Subject: Re: support for ARM GNU/Linux
Date: Wed, 14 Apr 1999 02:52:00 -0000	[thread overview]
Message-ID: <199904140952.KAA25068@sun52.NIS.cambridge> (raw)
Message-ID: <19990414025200.eflnMvOLVlZ3_XFmwd1LIE8vcgmJTbhik5WHglGzVAQ@z> (raw)
In-Reply-To: <37142B16.B43B5200@cygnus.com>

ac131313@cygnus.com said:
> I'm slightly curious about what is going on with all these different
> breakpoints (I should hasten to point out that I'm _not_ the ARM
> expert/maintainer :-).  Stan Shebs recently commited the change:

> 	1999-03-02  Stan Shebs  <shebs@andros.cygnus.com>

> 	From Gary Thomas  <gthomas@cygnus.co.uk>:
> 	* arm-tdep.c (ARM_LE_BREAKPOINT, ARM_BE_BREAKPOINT,
> 	THUMB_LE_BREAKPOINT, THUMB_BE_BREAKPOINT): Use illegal instruction
> 	instead of SWI 24.
> 	* config/arm/tm-arm.h (CALL_DUMMY): Ditto.
> 	(IN_SIGTRAMP): Define. 


A bit of history.  SWI 24 was the breakpoint swi in RISC iX, which the 
kernel understood (in some way).  I don't know if it was necessary to use 
exactly that SWI if you were using gdb or if the same effect could be 
achieved with other illegal instructions.

A side-note, before ARM Architecture v4 many "undefined" instruction 
formats aren't guaranteed to take the undefined instruction trap.  Also 
note that, in this respect, the ARM7TDMI is NOT fully ARM v4 compliant.

I don't know if anyone cares about RISC iX support any more (though gcc 
still supports it).

Richard.



  parent reply	other threads:[~1999-04-14  3:36 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
1999-04-12 12:26 Philip Blundell
1999-04-12 13:19 ` Scott Bambrough
1999-04-12 14:12   ` Scott Bambrough
1999-04-12 14:27   ` Philip Blundell
1999-04-12 20:18 ` Jim Blandy
1999-04-13  6:45   ` Philip Blundell
     [not found]   ` <E10X3Uv-0003Kd-00.cygnus.patches.gdb@fountain.nexus.co.uk>
1999-04-13 22:44     ` Andrew Cagney
1999-04-14  2:21       ` Philip Blundell
1999-04-14  3:36       ` Richard Earnshaw [this message]
1999-04-14  2:52         ` Richard Earnshaw
1999-04-14 11:34         ` Stan Shebs
1999-04-14 12:18           ` Richard Earnshaw
     [not found]   ` <37142B16.B43B5200.cygnus.patches.gdb@cygnus.com>
1999-04-13 23:56     ` Andrew Cagney

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