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Wed, 27 May 2026 11:16:00 -0700 (PDT) Received: from localhost ([212.73.77.104]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-4904526c926sm736405855e9.1.2026.05.27.11.15.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 27 May 2026 11:15:59 -0700 (PDT) From: Askar Safin To: Alejandro Colomar , linux-man@vger.kernel.org Cc: Christian Brauner , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] man/man3/errno.3: clarify ENOTSUP and EOPNOTSUPP Date: Wed, 27 May 2026 18:15:48 +0000 Message-ID: <20260527181549.2237547-1-safinaskar@gmail.com> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit As revealed by Christian Brauner recently ( https://lore.kernel.org/all/20260527-fotowettbewerb-abwinken-einfach-83db3411945b@brauner/ ), EOPNOTSUPP is widely used on Linux to mean "Operation not supported", as opposed to "Operation not supported on socket". Also, as seen in POSIX issue 8: https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/errno.h.html POSIX doesn't require ENOTSUP and EOPNOTSUPP to be distinct, so let's update that, too. Signed-off-by: Askar Safin --- man/man3/errno.3 | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/man/man3/errno.3 b/man/man3/errno.3 index a070dab..fdd2710 100644 --- a/man/man3/errno.3 +++ b/man/man3/errno.3 @@ -477,13 +477,14 @@ Name not unique on network. No such device or address (POSIX.1-2001). .TP .B EOPNOTSUPP -Operation not supported on socket (POSIX.1-2001). +Operation not supported (POSIX.1-2001). +According to POSIX.1 this is "Operation not supported on socket", +but on Linux it effectively means just "Operation not supported". .IP .RB ( ENOTSUP and .B EOPNOTSUPP -have the same value on Linux, but -according to POSIX.1 these error values should be distinct.) +have the same value on Linux.) .TP .B EOVERFLOW Value too large to be stored in data type (POSIX.1-2001). base-commit: 9a4bfd0e50745c2649b6291db40b58e37c9c1c6b -- 2.47.3