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Re: [Fwd: Fix arm_addr_bits_remove: 26-bit Thumb doesn't exist]
- To: Ben Harris <bjh21 at netbsd dot org>,Fernando Nasser <fnasser at redhat dot com>
- Subject: Re: [Fwd: Fix arm_addr_bits_remove: 26-bit Thumb doesn't exist]
- From: Nick Clifton <nickc at cambridge dot redhat dot com>
- Date: 22 Oct 2001 10:55:44 +0100
- Cc: <gdb-patches at sourceware dot cygnus dot com>
- References: <3BD301F6.D679AB69@redhat.com>
Hi Fernando, Hi Ben,
> From: Ben Harris <bjh21@netbsd.org>
>
> I haven't actually encountered this bug in reality yet, but it looks
> to me as if arm_addr_bits_remove() is bogus. Specifically, it has a
> case for Thumb state in a 26-bit mode. According to the ARM ARM
> (2nd Edition, section A8.1), no processor will support both 26-bit
> mode and thumb state at all, let alone at the same time. I suspect
> this might be a noticeable problem when debugging SVC mode code,
> since then R15 will have its bottom bit set, which arm_pc_is_thumb()
> is likely to interpret as meaning the CPU is in Thumb state.
>
> ChangeLog entry:
>
> 2001-10-20 Ben Harris <bjh21@netbsd.org>
>
> * arm-tdep.c (arm_addr_bits_remove): Don't believe in 26-bit
> Thumb.
This looks like a reasonable patch to me. I do not have the authority
to approve it, but I would certainly recommend it to the GDB
maintainers.
Cheers
Nick