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Re: Adding MIPS registers (was Re: [PATCH v2] Reset errno before PTRACE_PEEKUSER for MIPS DSP_CONTROL)
- From: Paul Burton <paul dot burton at imgtec dot com>
- To: James Hogan <james dot hogan at imgtec dot com>
- Cc: "Maciej W. Rozycki" <macro at codesourcery dot com>, <gdb at sourceware dot org>, Matthew Fortune <matthew dot fortune at imgtec dot com>
- Date: Wed, 10 Sep 2014 07:47:06 +0100
- Subject: Re: Adding MIPS registers (was Re: [PATCH v2] Reset errno before PTRACE_PEEKUSER for MIPS DSP_CONTROL)
- Authentication-results: sourceware.org; auth=none
- References: <1409608120-23991-1-git-send-email-james dot hogan at imgtec dot com> <alpine dot DEB dot 1 dot 10 dot 1409031340130 dot 27075 at tp dot orcam dot me dot uk> <20140903125111 dot GF12084 at jhogan-linux dot le dot imgtec dot org> <alpine dot DEB dot 1 dot 10 dot 1409031517450 dot 27075 at tp dot orcam dot me dot uk> <540F2ECD dot 5080604 at imgtec dot com> <alpine dot DEB dot 1 dot 10 dot 1409091808350 dot 27075 at tp dot orcam dot me dot uk> <20140909203922 dot GA27832 at jhogan-linux dot le dot imgtec dot org>
On Tue, Sep 09, 2014 at 09:39:22PM +0100, James Hogan wrote:
> > with the UFR
> > feature, so the register set presented will have to change dynamically,
> > according to that setting even for Linux targets.
>
> I have a feeling that UFR is currently unlikely to be enabled in Linux,
> due to subtleties with mode switches in multi-threaded processes
> requiring kernel support. Matthew or Paul (on CC) can probably confirm
> that.
Correct, UFR (along with UFE) is currently not enabled by Linux, and I'm
not aware of any need to deal with the pain involved in enabling it. There
is a need to switch mode across a whole process, which will need to be met
in some other way (the prctls in my internal branch, and hopefully the
same once upstream).
Paul