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authorGravatar Timo Ketola <Timo.Ketola@exertus.fi>2019-09-23 10:58:45 +0000
committerGravatar Yann E. MORIN <yann.morin.1998@free.fr>2020-04-25 14:06:34 +0200
commit98a6f1fc02e41ac30db24ac2b7262033faabacde (patch)
tree7b6c1a9be0ab5109c281e8cccc189510d00697bb /fs
parent74a865b1fc85352b814d032fa8725ace13f27eca (diff)
downloadbuildroot-98a6f1fc02e41ac30db24ac2b7262033faabacde.tar.gz
buildroot-98a6f1fc02e41ac30db24ac2b7262033faabacde.tar.bz2
fs/cpio: make initramfs init script survive 'console=' kernel argument
When booting with 'console=<empty>' in the kernel command line (as e.g. U-Boot does with silent flags in effect), opening /dev/console fails. As per POSIX [0], when iany redirection fails, the shell running exec shal exit in error. So, when 'console=<empty>' is specified. /dev/console can't be opened, and the redirection fails, and /init is killed. That behaviour was fixed on the kernel side with commit 2bd3a997befc2 (Open /dev/console from rootfs), present since 2.6.34, released in May 2010, so any [dr]ecent kernel will have that fix. Furthermore, busybox will fix things up anyway (in bb_sanitize_stdio()), falling back to opening /dev/null if no console is availble. systemd does a similar thing (in make_console_stdio()), and sysvinit again has a similar approach (in console_init()). The archealogy search turned up those relevant commits: 2011-08-04 10a130f91e initramfs/init: make sure that 0, 1, 2 fds are available introduces the three exec redirections in initramfs 2011-09-06 3fac21ef8d cpio: fix boot with dynamic /dev introduces the three exec redirections in cpio 2011-09-06 13a3afc536 fs/initramfs: refactor with fs/cpio dropped the initramfs tweaks to reuse the cpio ones 2012-11-04 e1ebae700a fs/common: Create initial console device introduces the /dev/console char,5,1 pseudo device creation in cpio 2018-03-31 dec061adce fs/cpio: don't extend packages' permissions table switched from the permission-table to a manual mknod to create /dev/console The redirections were added before we could guarantee there was a /dev/console in the rootfs. We're now guaranteed to have /dev/console in an initramfs, and any recent kernel will automatically open /dev/console before spawning /init. The three redirections are useless now, and cause harm under certain conditions. Drop them. [0] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_20_01 Signed-off-by: Timo Ketola <timo.ketola@exertus.fi> Cc: Peter Korsgaard <peter@korsgaard.com> [yann.morin.1998@free.fr: - extend commit log with the analysis done with Peter ] Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Diffstat (limited to 'fs')
-rwxr-xr-xfs/cpio/init3
1 files changed, 0 insertions, 3 deletions
diff --git a/fs/cpio/init b/fs/cpio/init
index dbe09ac68e..b0af18b67a 100755
--- a/fs/cpio/init
+++ b/fs/cpio/init
@@ -1,7 +1,4 @@
#!/bin/sh
# devtmpfs does not get automounted for initramfs
/bin/mount -t devtmpfs devtmpfs /dev
-exec 0</dev/console
-exec 1>/dev/console
-exec 2>/dev/console
exec /sbin/init "$@"