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[14.201.155.8]) by smtp.gmail.com with ESMTPSA id c191sm5878014pfc.94.2021.05.19.00.55.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 May 2021 00:55:40 -0700 (PDT) Date: Wed, 19 May 2021 17:55:35 +1000 From: Nicholas Piggin Subject: Re: Linux powerpc new system call instruction and ABI To: Joakim Tjernlund , "ldv@altlinux.org" , "mpe@ellerman.id.au" References: <20200611081203.995112-1-npiggin@gmail.com> <20210518231331.GA8464@altlinux.org> <9b5ea7059c5a5d4e9ccccd7d73ce2c66b2203f52.camel@infinera.com> In-Reply-To: <9b5ea7059c5a5d4e9ccccd7d73ce2c66b2203f52.camel@infinera.com> MIME-Version: 1.0 Message-Id: <1621410291.c7si38sa9q.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "libc-dev@lists.llvm.org" , "musl@lists.openwall.com" , "linuxppc-dev@lists.ozlabs.org" , "linux-api@vger.kernel.org" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Excerpts from Joakim Tjernlund's message of May 19, 2021 5:33 pm: > On Wed, 2021-05-19 at 02:13 +0300, Dmitry V. Levin wrote: >> Hi, >>=20 >> On Thu, Jun 11, 2020 at 06:12:01PM +1000, Nicholas Piggin wrote: >> [...] >> > - Error handling: The consensus among kernel, glibc, and musl is to mo= ve to >> > =C2=A0=C2=A0using negative return values in r3 rather than CR0[SO]=3D1= to indicate error, >> > =C2=A0=C2=A0which matches most other architectures, and is closer to a= function call. >=20 > What about syscalls like times(2) which can return -1 without it being an= error? They do become errors / indistinguishable and have to be dealt with by=20 libc or userspace. Which does follow what most architectures do (all=20 except ia64, mips, sparc, and powerpc actually). Interesting question though, it should have been noted. Thanks, Nick