3.11.y kernel config options which prevent boot...

[srcshelton]

Hi all,

I've been testing various options to build an efficient rpi-3.11.y kernel, and I'm finding that the following prevent boot from succeeding if set:

Code: Select all

CONFIG_KUSER_HELPERS
CONFIG_SLOB

... disabling the former (which failed to compile on rpi-3.10.y, where is was introduced) removes a potentially-exploitable fixed-address which provides multi-CPU compatibility for generic kernels. However, with this removed the kernel crashes immediately on entering user-space with a 'Attempted to kill init' panic.

The latter option provides a much simpler and lighter-weight slab-allocator for uniprocessor systems - but with this enabled, the kernel freezes at the point where it should enter user-space.

I have make use of an initial ramdisk in order to mount a RAID-1 btrfs root filesystem, and in both cases the initrd code is not executed (although I do see 'Unpacking initramfs...' in the kernel output)... I'm not sure of the significance of this. The two systems I'm testing on boot successfully (having loaded the initramfs file) with either older kernel versions, or with an rpi-3.11.y kernel with the above options set and unset respectively.

Could anyone else confirm or deny these observations, so that I can check that it's not just me or a quirk of my Pis or my setup?

Cheers,

Stuart

[AndrewS]

https://github.com/raspberrypi/linux/issues might be a better place to ask about this? *shrug*

[srcshelton]

I was hoping to confirm that these are actually issues before reporting them... not much point if no-one else is affected.