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[222.152.189.137]) by smtp.gmail.com with ESMTPSA id p3sm8288931pjt.0.2021.07.07.21.33.10 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 07 Jul 2021 21:33:12 -0700 (PDT) Subject: Re: [PATCH RFC v2] m68k: remove get_fs()/set_fs() To: Christoph Hellwig , Linus Torvalds References: <1625708899-29013-1-git-send-email-schmitzmic@gmail.com> <20210708043145.GB17672@lst.de> Cc: Geert Uytterhoeven , linux-m68k From: Michael Schmitz Message-ID: <38991687-7b33-994b-b7d3-22400872a45a@gmail.com> Date: Thu, 8 Jul 2021 16:33:08 +1200 User-Agent: Mozilla/5.0 (X11; Linux ppc; rv:45.0) Gecko/20100101 Icedove/45.4.0 MIME-Version: 1.0 In-Reply-To: <20210708043145.GB17672@lst.de> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-m68k@vger.kernel.org Hi Christoph, Am 08.07.2021 um 16:31 schrieb Christoph Hellwig: > On Wed, Jul 07, 2021 at 08:01:33PM -0700, Linus Torvalds wrote: >> The '#' turns the argument into a string, but it was already >> _supposed_ to be a string. But no, the problem is that it turns the >> macro name MOVES into the _string_ "MOVES". >> >> Which happens to compile just fine, because "moves" is a real >> instruction. But it's actually _meant_ to be a macro that expands to >> either the string "moves" or "move". >> >> So what happens is that at least in Christoph's version, I think the >> code _always_ uses "MOVES", even in configurations where the macro >> MOVES should have just become "move". >> >> So it all builds fine, looks fine to the assembler, but it uses the >> wrong instruction. >> >> Macro expansion with the '#' character and other macros used as >> arguments is something people need to be very careful with. It's why >> we have a whole header file for just the "stringify" operation, see >> >> >> But in this case, it shouldn't have used '#' at all, since the >> argument was already a string, and never needed to be turned into a >> string by the pre-processor. > > Yes, that problem exists, but just removing the # causes "inst" to go > into the cpp output. Let me brush up my cpp-foo. Putting quotes around 'inst' makes it compile for me. Cheers, Michael