Message-ID: <20250913003842.41944-19-safinaskar@gmail.com>
Date: Sat, 13 Sep 2025 00:37:57 +0000
From: Askar Safin <safinaskar@...il.com>
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Subject: [PATCH RESEND 18/62] doc: modernize Documentation/driver-api/early-userspace/early_userspace_support.rst

Update it to reflect initrd removal

Signed-off-by: Askar Safin <safinaskar@...il.com>
---
 .../early_userspace_support.rst                | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/Documentation/driver-api/early-userspace/early_userspace_support.rst b/Documentation/driver-api/early-userspace/early_userspace_support.rst
index 61bdeac1bae5..0ca923c1007b 100644
--- a/Documentation/driver-api/early-userspace/early_userspace_support.rst
+++ b/Documentation/driver-api/early-userspace/early_userspace_support.rst
@@ -127,28 +127,22 @@ mailing list at https://www.zytor.com/mailman/listinfo/klibc
 How does it work?
 =================
 
-The kernel has currently 3 ways to mount the root filesystem:
+The kernel has currently 2 ways to mount the root filesystem:
 
 a) all required device and filesystem drivers compiled into the kernel, no
-   initrd.  init/main.c:init() will call prepare_namespace() to mount the
+   initramfs.  init/main.c:kernel_init_freeable() will call prepare_namespace() to mount the
    final root filesystem, based on the root= option and optional init= to run
-   some other init binary than listed at the end of init/main.c:init().
+   some other init binary than listed at the end of init/main.c:kernel_init().
 
-b) some device and filesystem drivers built as modules and stored in an
-   initrd.  The initrd must contain a binary '/linuxrc' which is supposed to
-   load these driver modules.  It is also possible to mount the final root
-   filesystem via linuxrc and use the pivot_root syscall.  The initrd is
-   mounted and executed via prepare_namespace().
-
-c) using initramfs.  The call to prepare_namespace() must be skipped.
+b) using initramfs.  The call to prepare_namespace() must be skipped.
    This means that a binary must do all the work.  Said binary can be stored
    into initramfs either via modifying usr/gen_init_cpio.c or via the new
-   initrd format, an cpio archive.  It must be called "/init".  This binary
+   initramfs format, an cpio archive.  It must be called "/init".  This binary
    is responsible to do all the things prepare_namespace() would do.
 
    To maintain backwards compatibility, the /init binary will only run if it
    comes via an initramfs cpio archive.  If this is not the case,
-   init/main.c:init() will run prepare_namespace() to mount the final root
+   init/main.c:kernel_init_freeable() will run prepare_namespace() to mount the final root
    and exec one of the predefined init binaries.
 
 Bryan O'Sullivan <bos@...pentine.com>
-- 
2.47.2

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