From: Christian Brauner <brauner@kernel.org>
To: Farid Zakaria <farid.m.zakaria@gmail.com>,
linux-fsdevel@vger.kernel.org
Cc: Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>, Kees Cook <kees@kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Jan Kara <jack@suse.cz>, Jonathan Corbet <corbet@lwn.net>,
linux-mm@kvack.org, bpf@vger.kernel.org, jannh@google.com,
mail@johnericson.me,
"Christian Brauner (Amutable)" <brauner@kernel.org>
Subject: [PATCH 02/21] docs, binfmt_misc: keep general usage out of the handler sections
Date: Mon, 20 Jul 2026 11:33:25 +0200 [thread overview]
Message-ID: <20260720-work-bpf-binfmt_misc-ptinterp-v1-2-ddb76c9a508e@kernel.org> (raw)
In-Reply-To: <20260720-work-bpf-binfmt_misc-ptinterp-v1-0-ddb76c9a508e@kernel.org>
The general usage trails the bpf-backed handlers section and therefore
reads as part of it. It predates that section and applies to binfmt_misc
as a whole.
Move it back up so the handler section ends where the file does.
Upcoming sections describing the transparent and loader dispatch modes
append after it without swallowing the general prose again.
Pure text move, no content changes.
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
Documentation/admin-guide/binfmt-misc.rst | 79 ++++++++++++++++---------------
1 file changed, 40 insertions(+), 39 deletions(-)
diff --git a/Documentation/admin-guide/binfmt-misc.rst b/Documentation/admin-guide/binfmt-misc.rst
index 7f42abf9cfba..c76381a4bcad 100644
--- a/Documentation/admin-guide/binfmt-misc.rst
+++ b/Documentation/admin-guide/binfmt-misc.rst
@@ -100,6 +100,46 @@ There are some restrictions:
- the interpreter string may not exceed 127 characters
+To use binfmt_misc you have to mount it first. You can mount it with
+``mount -t binfmt_misc none /proc/sys/fs/binfmt_misc`` command, or you can add
+a line ``none /proc/sys/fs/binfmt_misc binfmt_misc defaults 0 0`` to your
+``/etc/fstab`` so it auto mounts on boot.
+
+You may want to add the binary formats in one of your ``/etc/rc`` scripts during
+boot-up. Read the manual of your init program to figure out how to do this
+right.
+
+Think about the order of adding entries! Later added entries are matched first!
+
+
+A few examples (assumed you are in ``/proc/sys/fs/binfmt_misc``):
+
+- enable support for em86 (like binfmt_em86, for Alpha AXP only)::
+
+ echo ':i386:M::\x7fELF\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x03:\xff\xff\xff\xff\xff\xfe\xfe\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfb\xff\xff:/bin/em86:' > register
+ echo ':i486:M::\x7fELF\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x06:\xff\xff\xff\xff\xff\xfe\xfe\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfb\xff\xff:/bin/em86:' > register
+
+- enable support for packed DOS applications (pre-configured dosemu hdimages)::
+
+ echo ':DEXE:M::\x0eDEX::/usr/bin/dosexec:' > register
+
+- enable support for Windows executables using wine::
+
+ echo ':DOSWin:M::MZ::/usr/local/bin/wine:' > register
+
+For java support see Documentation/admin-guide/java.rst
+
+
+You can enable/disable binfmt_misc or one binary type by echoing 0 (to disable)
+or 1 (to enable) to ``/proc/sys/fs/binfmt_misc/status`` or
+``/proc/.../the_name``.
+Catting the file tells you the current status of ``binfmt_misc/the_entry``.
+
+You can remove one entry or all entries by echoing -1 to ``/proc/.../the_name``
+or ``/proc/sys/fs/binfmt_misc/status``. A single entry can also be removed
+by simply unlinking (``rm``) ``/proc/.../the_name``.
+
+
bpf-backed handlers
-------------------
@@ -157,45 +197,6 @@ registered in, falling back to ancestor namespaces, mirroring how
binfmt_misc instances themselves are looked up. The entry keeps the handler
alive; deleting the struct_ops map only prevents new activations.
-To use binfmt_misc you have to mount it first. You can mount it with
-``mount -t binfmt_misc none /proc/sys/fs/binfmt_misc`` command, or you can add
-a line ``none /proc/sys/fs/binfmt_misc binfmt_misc defaults 0 0`` to your
-``/etc/fstab`` so it auto mounts on boot.
-
-You may want to add the binary formats in one of your ``/etc/rc`` scripts during
-boot-up. Read the manual of your init program to figure out how to do this
-right.
-
-Think about the order of adding entries! Later added entries are matched first!
-
-
-A few examples (assumed you are in ``/proc/sys/fs/binfmt_misc``):
-
-- enable support for em86 (like binfmt_em86, for Alpha AXP only)::
-
- echo ':i386:M::\x7fELF\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x03:\xff\xff\xff\xff\xff\xfe\xfe\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfb\xff\xff:/bin/em86:' > register
- echo ':i486:M::\x7fELF\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x06:\xff\xff\xff\xff\xff\xfe\xfe\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfb\xff\xff:/bin/em86:' > register
-
-- enable support for packed DOS applications (pre-configured dosemu hdimages)::
-
- echo ':DEXE:M::\x0eDEX::/usr/bin/dosexec:' > register
-
-- enable support for Windows executables using wine::
-
- echo ':DOSWin:M::MZ::/usr/local/bin/wine:' > register
-
-For java support see Documentation/admin-guide/java.rst
-
-
-You can enable/disable binfmt_misc or one binary type by echoing 0 (to disable)
-or 1 (to enable) to ``/proc/sys/fs/binfmt_misc/status`` or
-``/proc/.../the_name``.
-Catting the file tells you the current status of ``binfmt_misc/the_entry``.
-
-You can remove one entry or all entries by echoing -1 to ``/proc/.../the_name``
-or ``/proc/sys/fs/binfmt_misc/status``. A single entry can also be removed
-by simply unlinking (``rm``) ``/proc/.../the_name``.
-
Hints
-----
--
2.53.0
next prev parent reply other threads:[~2026-07-20 9:34 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-20 9:33 [PATCH 00/21] binfmt_misc: transparent interpreters and PT_INTERP loader substitution Christian Brauner
2026-07-20 9:33 ` [PATCH 01/21] exec: do not act on a stale execfd request without an executable Christian Brauner
2026-07-20 9:33 ` Christian Brauner [this message]
2026-07-20 9:33 ` [PATCH 03/21] binfmt_misc: table-drive the register string flags Christian Brauner
2026-07-20 9:33 ` [PATCH 04/21] binfmt_misc: normalize the per-exec invocation flags Christian Brauner
2026-07-20 9:33 ` [PATCH 05/21] binfmt_misc: split out entry_open_interpreter() Christian Brauner
2026-07-20 9:33 ` [PATCH 06/21] binfmt_misc: split out build_interp_argv() Christian Brauner
2026-07-20 9:33 ` [PATCH 07/21] exec: release the replaced file with do_close_execat() Christian Brauner
2026-07-20 9:33 ` [PATCH 08/21] exec: add AT_FLAGS_TRANSPARENT_INTERP Christian Brauner
2026-07-20 9:33 ` [PATCH 09/21] exec: label mm->exe_file with the binary for a transparent dispatch Christian Brauner
2026-07-20 9:33 ` [PATCH 10/21] binfmt_misc: add transparent interpreter dispatch Christian Brauner
2026-07-20 9:33 ` [PATCH 11/21] binfmt_misc: add a static transparent flag 'T' Christian Brauner
2026-07-20 9:33 ` [PATCH 12/21] binfmt_misc: let a bpf handler run the interpreter transparently Christian Brauner
2026-07-20 9:33 ` [PATCH 13/21] selftests/exec: convert the binfmt_misc bpf test to the kselftest harness Christian Brauner
2026-07-20 9:33 ` [PATCH 14/21] selftests/exec: test the transparent binfmt_misc mode Christian Brauner
2026-07-20 9:33 ` [PATCH 15/21] binfmt_misc: document the transparent identity contract Christian Brauner
2026-07-20 9:33 ` [PATCH 16/21] exec: carry a PT_INTERP substitute in struct linux_binprm Christian Brauner
2026-07-20 9:33 ` [PATCH 17/21] binfmt_elf: consume a stashed PT_INTERP substitute Christian Brauner
2026-07-20 9:33 ` [PATCH 18/21] binfmt_misc: add the 'L' loader substitution flag Christian Brauner
2026-07-20 9:33 ` [PATCH 19/21] binfmt_misc: let a bpf handler request loader substitution Christian Brauner
2026-07-20 9:33 ` [PATCH 20/21] selftests/exec: test binfmt_misc " Christian Brauner
2026-07-20 9:33 ` [PATCH 21/21] binfmt_misc: document " Christian Brauner
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