In-Reply-To: <20090709210356.B1FD96BA56@magilla.sf.frob.com>
To: Roland McGrath <roland@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>, Christoph Hellwig <hch@infradead.org>,
       linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
       Linus Torvalds <torvalds@linux-foundation.org>
MIME-Version: 1.0
Subject: Re: [PATCH] score: add regsets support for score
Message-ID: <OFE8F25211.6F919E29-ON482575EF.0031BE0C-482575EF.00328689@sunplusct.com>
From: liqin.chen@sunplusct.com
Date: Fri, 10 Jul 2009 17:06:27 +0800
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Sender: linux-kernel-owner@vger.kernel.org
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Roland McGrath <roland@redhat.com> д?? 2009-07-10 05:03:56:

> > > +       ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> > > +                                 regs->regs,
> > > +                                 offsetof(struct pt_regs, regs),
> > > +                                 end_pos);
> 
> This looks odd to me.  The last two arguments here are offsets into
> the userland ABI format defined by the user_regset layout.  Unless
> offsetof(struct pt_regs, regs) is zero, then you need to precede
> this call with one that fills in the initial stretch of the userland
> format layout from its 0 up to offsetof(struct pt_regs, regs).  If
> in fact offsetof(struct pt_regs, regs) is zero, then it would be far
> less confusing to just write 0 there IMHO.  Using offsetof on
> pt_regs at all here is very confusing to me unless pt_regs describes
> the userland ABI layout (in which case the use here still doesn't
> make sense).

Thanks Roland,

Maybe I misunderstand the arguments meaning of
user_regset_copy(in/out), I rewrite these code,
use userland ABI format the same as score's pt_regs, 
just like sh arch do, maybe it's easy to understand.
It will be sent out latter.

Best Regards
Liqin
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