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Message-ID: <20170726134616.grjb7metn7rv5alu@ltop.local>
Date: Wed, 26 Jul 2017 15:46:17 +0200
From: Luc Van Oostenryck <luc.vanoostenryck@...il.com>
To: Lance Richardson <lrichard@...hat.com>
Cc: Stephen Boyd <sboyd@...eaurora.org>, linux-sparse@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: Sparse warnings on GENMASK + arm32
On Wed, Jul 26, 2017 at 09:33:01AM -0400, Lance Richardson wrote:
> > From: "Stephen Boyd" <sboyd@...eaurora.org>
> > I see sparse warning when I check a clk driver file in the kernel
> > on a 32-bit ARM build.
> >
> > drivers/clk/sunxi/clk-sun6i-ar100.c:65:20: warning: cast truncates bits from
> > constant value (3ffffffff becomes ffffffff)
>
> Hmm, it seems sparse is incorrectly taking ~0UL to be a 64-bit value
> while BITS_PER_LONG is (correctly) evaluated to be 32.
>
> #define GENMASK(h, l) \
> (((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
It's the kernel CHECKFLAGS that should be using -m32/-m64 if built
on a machine with a different wordsize tht the arch.
I sent earlier a patch for ARM, I just forgot to CC the mailing list here.
-- Luc
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