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[189.203.100.42]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-2e3c075b1fdsm5117089fac.24.2025.05.26.15.01.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 May 2025 15:01:56 -0700 (PDT) Date: Mon, 26 May 2025 16:01:55 -0600 From: Tom Rini To: Rasmus Villemoes Cc: u-boot@lists.denx.de, Daniel Schwierzeck , Joe Hershberger Subject: Re: [PATCH 0/4] list.h/treewide: get rid of no-op prefetch() Message-ID: <20250526220155.GE100073@bill-the-cat> References: <20250507121246.518691-1-ravi@prevas.dk> <20250522165656.GB2179216@bill-the-cat> <87r00c3143.fsf@prevas.dk> <20250525230201.GS100073@bill-the-cat> <87msaz2i46.fsf@prevas.dk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="Ku+sL/Kd2ziupSlS" Content-Disposition: inline In-Reply-To: <87msaz2i46.fsf@prevas.dk> X-Clacks-Overhead: GNU Terry Pratchett X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.39 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" X-Virus-Scanned: clamav-milter 0.103.8 at phobos.denx.de X-Virus-Status: Clean --Ku+sL/Kd2ziupSlS Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, May 26, 2025 at 11:10:33PM +0200, Rasmus Villemoes wrote: > On Sun, May 25 2025, Tom Rini wrote: >=20 > > On Sun, May 25, 2025 at 10:07:56PM +0200, Rasmus Villemoes wrote: > >>=20 > >> :( so we've been relying on that prefetch() laundering away the > >> volatile. > >>=20 > >> Which really begs the question: Why, exactly, is it that gd even has > >> that volatile qualifier in the first place?=20 > > > > The answer is likely early 2000s GCC. > > > >> I'm 98% certain that we could drop that and get better code generation > >> and avoid a ton of places where we cast away that volatile which > >> shouldn't really be there anyway. > > > > It would be a good thing to experiment with now and maybe try for real > > in a near-future merge window. >=20 > So since it's declared per architecture I just tried with arm for now, > and this >=20 > diff --git a/arch/arm/include/asm/global_data.h b/arch/arm/include/asm/gl= obal_data.h > index 45401d5e3c8..f7a47204b7c 100644 > --- a/arch/arm/include/asm/global_data.h > +++ b/arch/arm/include/asm/global_data.h > @@ -133,9 +133,9 @@ static inline gd_t *get_gd(void) > #else > =20 > #ifdef CONFIG_ARM64 > -#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *g= d asm ("x18") > +#define DECLARE_GLOBAL_DATA_PTR register gd_t *gd asm ("x= 18") > #else > -#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *g= d asm ("r9") > +#define DECLARE_GLOBAL_DATA_PTR register gd_t *gd asm ("r= 9") > #endif > #endif > =20 >=20 > builds, boots to linux, and passes our test suite on our > beagleboneblack, imx7 SabreSD, RPi 3, RPi 4, RPi-cm4, wandboard, > imx8mp-evk; i.e. a good mix of 32 and 64 bit arm. That's a good set of datapoints, thanks. Do you want to post a real series at some point or should I do it and Suggested-by you? Thanks. --=20 Tom --Ku+sL/Kd2ziupSlS Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQGzBAABCgAdFiEEGjx/cOCPqxcHgJu/FHw5/5Y0tywFAmg05NIACgkQFHw5/5Y0 tyzGkQv/ZSUT6MArS2ZLc99kU9otVF0MDwQFWg1rj3W+qP/W51jTWrf8cU1pzL1g o0fIwp2tVBEfxkKlOGTumFZyQIKRGULyUmOLp4CarYSwCynFD9v2n8K1yqeIdWKQ NBf1K5glWhekSGt9aGtrSSLVyQW5XHeBGJS1UvtIiXVFKCr7usLRbUqvzWjPo1rl 3Ki8ynDSB3CD281vs5EZLwFoC+xwO80I16Mp0cHGNXOAuGd2i4TywfCTnzXiJq8V nfHaWmwBNSoKKb6UrexaNI7gcVzRKRcgRUMeHRDTck5nu2X9kfurpEtgrMY8xrZU cxxTexKrcrG3HA3MMSENUgJ1PnNtwjuytT3Z5Fq4SqKEsCqEuG5yoUSdelH5xRLD Rrnb9v9xG06OSjr0IAwIau5z6heyhi1eF0b/h3oBPp7NN9SRs2mf57pki02VPEVT 58steVBj+tUBch8jn3tOM6vYrUTFCzfMaAMJPA0YFJPP3NdASu1m02kLZEZHl0O4 sQlXdSxk =X5nB -----END PGP SIGNATURE----- --Ku+sL/Kd2ziupSlS--