On 05/09/2017 04:31 PM, Andrew Morton wrote: > On Thu, 4 May 2017 16:09:06 -0500 Rob Landley <[email protected]> wrote: > >> From: Rob Landley <[email protected]> >> >> Make initramfs honor CONFIG_DEVTMPFS_MOUNT, and move >> /dev/console open after devtmpfs mount. > > > Could we please see complete description of the runtime effects of this > change? How does it affect users? How does it benefit users?
It makes the behavior consistent. If you're going to have the config symbol anyway, why is initramfs a second class citizen? That said, I was fixing a specific bug when I started the patch: when you statically link in an initramfs by pointing the kernel build at a directory (so it makes its own cpio archive from that), if you're not running the build as root you can't create dev/console in there and there's no obvious way to add nodes (like you can editing the gen_initramfs_list) output. This means there's no /dev/console when init gets launched, so PID 1's stdin/stdout/stderr go nowhere, and until your init script can open its own and redirect you get no output if something goes wrong, so debugging is fiddly and there's a hole where output gets lost. Userspace can't close that hole. When making the patch I did a version that mounted /proc /sys and /dev/pts too, so rdinit=/bin/sh had pretty much its full environment without an init script just like the DEVTMPFS_MOUNT option's help text implied... but that seemed unlikely to be accepted. The console gap is a problem userspace can't fix, the rest userspace can, so I did the minimal thing. > The DEVTMPFS_MOUNT Kconfig help (drivers/base/Kconfig) says: > > This option does not affect initramfs based booting, here > the devtmpfs filesystem always needs to be mounted manually > after the rootfs is mounted. > > which seems to no longer be correct? Ah, sorry. I rewrote the help text and didn't include that file in the diff. And rechecking I see the override part wasn't implemented by my patch, I'll send a new one. Rob
