Re: [PATCH 4/4] pre_init: add ARM implementations

[Will Deacon <will.deacon@arm.com>]

On Wed, Feb 24, 2016 at 03:33:08PM +0000, Andre Przywara wrote:
> The pre_init stub consists of two syscalls mouting the host's FS
> via 9pfs and then calling the actual init binary, which can now
> use normal dynamic linking.
> Based on the x86 code provide an ARM and ARM64 implementation of
> that. Beside removing the need for static linkage it reduces the
> size of the kvmtool binary by quite a lot (numbers for aarch64):
> 
> -rwxr-xr-x 1 root root     9952 Nov 16 14:37 guest/init
> -rwxr-xr-x 1 root root      512 Nov 16 14:37 guest/pre_init
> -rwxr-xr-x 2 root root  1284704 Nov 16 14:37 lkvm
> vs. the old version:
> -rwxr-xr-x 1 root root   776024 Nov 16 14:38 guest/init
> -rwxr-xr-x 2 root root  2050112 Nov 16 14:38 lkvm
> 
> Tested on Midway and Juno.

Hmm, I'm not super keen on switching behaviour like this on arm, where
it's not uncommon to build a static lkvm and transfer it to a remote
target and expect init to work.

Perhaps we could only do this when building a dynamic executable?

Will