From ee3db4b8660d709be0a112e56d379b918a607234 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Tue, 21 Jul 2026 16:13:44 +0200 Subject: [PATCH] docs, binfmt_misc: keep general usage out of the handler sections 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. Link: https://patch.msgid.link/20260721-work-bpf-binfmt_misc-ptinterp-v2-2-e57866e4ae0f@kernel.org Reviewed-by: Farid Zakaria Signed-off-by: Christian Brauner (Amutable) --- 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 557c8eadb9df..9f0d9132723f 100644 --- a/Documentation/admin-guide/binfmt-misc.rst +++ b/Documentation/admin-guide/binfmt-misc.rst @@ -104,6 +104,46 @@ There are some restrictions: the binary +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 ------------------- @@ -162,45 +202,6 @@ handler registered in the same user namespace as its binfmt_misc instance. 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 -----