path: root/usr
diff options
authorFlorian Fainelli <>2017-06-02 14:46:22 -0700
committerLinus Torvalds <>2017-06-02 15:07:37 -0700
commit57ddfdaa9a72fe726a44d26d99db31bc137dbeff (patch)
treef7124bce5586593aaf50830508a401576206c29c /usr
parent4f4f2ba9c531b3d7cee293dd3654ba3b86e7d220 (diff)
initramfs: fix disabling of initramfs (and its compression)
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/" CONFIG_INITRAMFS_ROOT_UID=1000 CONFIG_INITRAMFS_ROOT_GID=1000 CONFIG_INITRAMFS_COMPRESSION_NONE=y CONFIG_INITRAMFS_COMPRESSION="" Commit db2aa7fd15e85 ("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 9e3596b0c6539e ("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") Link: Signed-off-by: Florian Fainelli <> Acked-by: Nicholas Piggin <> Cc: P J P <> Cc: Paul Bolle <> Cc: Michal Marek <> Cc: Daniel Thompson <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'usr')
1 files changed, 1 insertions, 0 deletions
diff --git a/usr/Kconfig b/usr/Kconfig
index c0c4850..ad0543e 100644
--- a/usr/Kconfig
+++ b/usr/Kconfig
@@ -220,6 +220,7 @@ config INITRAMFS_COMPRESSION_LZ4
+ depends on INITRAMFS_SOURCE!=""
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