linux-kernel - [RFC PATCH 9/9] fs/binfmt_elf_fdpic: Reflect that PIE binaries also work in KConfig help

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Message-ID: <20260131074440.732588-10-daniel@thingy.jp>
Date: Sat, 31 Jan 2026 16:44:40 +0900
From: Daniel Palmer <daniel@...ngy.jp>
To: linux@...ssschuh.net,
	w@....eu
Cc: kees@...nel.org,
	linux-kernel@...r.kernel.org,
	Daniel Palmer <daniel@...ngy.jp>
Subject: [RFC PATCH 9/9] fs/binfmt_elf_fdpic: Reflect that PIE binaries also work in KConfig help

Since commit 1bde925d2354 ("fs/binfmt_elf_fdpic.c: provide NOMMU loader for regular ELF binaries")
it has been possible to load some normal ELF binaries on nommu but it
wasn't documented in the help.

Since nolibc can generate static-pie binaries that work with this loader
document that normal ELFs can work as long as they are PIE and you have
a linker and that nolibc can also generate static-PIE binaries that
can load without any assitance.

Signed-off-by: Daniel Palmer <daniel@...ngy.jp>
---
 fs/Kconfig.binfmt | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index 1949e25c7741..71573bfd32ac 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -69,6 +69,16 @@ config BINFMT_ELF_FDPIC
 
 	  It is also possible to run FDPIC ELF binaries on MMU linux also.
 
+	  On nommu systems this can also load normal ELF binaries as long as
+	  the binary is linked as PIE. If the binary is not static PIE, does not
+	  include it's own relocation code, this requires a linker like uldso to
+	  be present and set as the interpreter.
+
+	  nolibc included in the kernel source can create static-PIE binaries
+	  by including relocation code and the resulting binaries run on MMU
+	  systems with the normal ELF loader and on nommu systems with this
+	  loader.
+
 config ELFCORE
 	bool
 	help
-- 
2.51.0