From: Florian Fainelli <f.fainelli@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: npiggin@gmail.com, ppandit@redhat.com, pebolle@tiscali.nl,
mmarek@suse.cz, Florian Fainelli <f.fainelli@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Francisco Blas Izquierdo Riera (klondike)"
<klondike@xiscosoft.net>,
Daniel Thompson <daniel.thompson@linaro.org>
Subject: [PATCH] initramfs: Fix disabling of initramfs (and its compression)
Date: Sat, 20 May 2017 20:33:35 -0700
Message-ID: <20170521033337.6197-1-f.fainelli@gmail.com> (raw)
Commit db2aa7fd15e8 ("initramfs: allow again choice of the embedded
initram compression algorithm") introduced the possibility to select the
initramfs compression algorithm from Kconfig and while this is a nice
feature it broke the use case described below.
Here is what my build system does:
- kernel is initially configured not to have an initramfs included
- build the user space root file system
- re-configure the kernel to have an initramfs included
(CONFIG_INITRAMFS_SOURCE="/path/to/romfs") and set relevant
CONFIG_INITRAMFS options, in my case, no compression option
(CONFIG_INITRAMFS_COMPRESSION_NONE)
- kernel is re-built with these options -> kernel+initramfs image is
copied
- kernel is re-built again without these options -> kernel image is
copied
Building a kernel without an initramfs means setting this option:
CONFIG_INITRAMFS_SOURCE="" (and this one only)
whereas building a kernel with an initramfs means setting these options:
CONFIG_INITRAMFS_SOURCE="/home/fainelli/work/uclinux-rootfs/romfs
/home/fainelli/work/uclinux-rootfs/misc/initramfs.dev"
CONFIG_INITRAMFS_ROOT_UID=1000
CONFIG_INITRAMFS_ROOT_GID=1000
CONFIG_INITRAMFS_COMPRESSION_NONE=y
CONFIG_INITRAMFS_COMPRESSION=""
Commit db2aa7fd15e857891cefbada8348c8d938c7a2bc ("initramfs: allow again
choice of the embedded initram compression algorithm") is problematic
because CONFIG_INITRAMFS_COMPRESSION which is used to determine the
initramfs_data.cpio extension/compression is a string, and due to how
Kconfig works it will evaluate in order, how to assign it.
Setting CONFIG_INITRAMFS_COMPRESSION_NONE with
CONFIG_INITRAMFS_SOURCE="" cannot possibly work (because of the depends
on INITRAMFS_SOURCE!="" imposed on CONFIG_INITRAMFS_COMPRESSION ) yet we
still get CONFIG_INITRAMFS_COMPRESSION assigned to ".gz" because
CONFIG_RD_GZIP=y is set in my kernel, even when there is no initramfs
being built.
So we basically end-up generating two initramfs_data.cpio* files, one
without extension, and one with .gz. This causes usr/Makefile to track
usr/initramfs_data.cpio.gz, and not usr/initramfs_data.cpio anymore,
that is also largely problematic after
9e3596b0c6539e28546ff7c72a06576627068353 ("kbuild: initramfs cleanup,
set target from Kconfig") because we used to track all possible
initramfs_data files in the $(targets) variable before that commit.
The end result is that the kernel with an initramfs clearly does not
contain what we expect it to, it has a stale initramfs_data.cpio file
built into it, and we keep re-generating an initramfs_data.cpio.gz file
which is not the one that we want to include in the kernel image proper.
The fix consists in hiding CONFIG_INITRAMFS_COMPRESSION when
CONFIG_INITRAMFS_SOURCE="". This puts us back in a state to the pre-4.10
behavior where we can properly disable and re-enable initramfs within
the same kernel .config file, and be in control of what
CONFIG_INITRAMFS_COMPRESSION is set to.
Fixes: db2aa7fd15e8 ("initramfs: allow again choice of the embedded initram compression algorithm")
Fixes: 9e3596b0c653 ("kbuild: initramfs cleanup, set target from Kconfig")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
usr/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/usr/Kconfig b/usr/Kconfig
index c0c48507e44e..ad0543e21760 100644
--- a/usr/Kconfig
+++ b/usr/Kconfig
@@ -220,6 +220,7 @@ config INITRAMFS_COMPRESSION_LZ4
endchoice
config INITRAMFS_COMPRESSION
+ depends on INITRAMFS_SOURCE!=""
string
default "" if INITRAMFS_COMPRESSION_NONE
default ".gz" if INITRAMFS_COMPRESSION_GZIP
--
2.9.3
next reply index
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-21 3:33 Florian Fainelli [this message]
2017-05-22 2:46 ` Nicholas Piggin
2017-08-28 20:03 ` Florian Fainelli
2017-08-29 3:09 ` Nicholas Piggin
2017-08-29 3:52 ` Florian Fainelli
2017-09-07 12:50 ` Florian Fainelli
2017-09-07 13:19 ` Nicholas Piggin
2017-09-08 4:36 ` Florian Fainelli
2017-09-14 22:59 ` Florian Fainelli
2017-09-15 0:41 ` Nicholas Piggin
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