linux kernel fallback syslinux config

alpine linux 3.5.2 works great.
i prefer edge version, so i am using it.
sometimes, it very unstable if newer kernel unstable,
i couldn't boot at all. i need backup kernel.

here is how i did.

# vi /sbin/setup-disk +802
- local boot_size=${BOOT_SIZE:-100} // boot size 100MB
+ local boot_size=${BOOT_SIZE:-1024} // boot size 1GB

after installation

# cp vmlinuz-grsec vmlinuz-grsec-fallback
# cp initramfs-linux-grsec initramfs-linux-grsec-fallback

# vi /boot/extlinux.conf

Label grsec
MENU DEFAULT
MENU LABEL Linux grsec
LINUX vmlinuz-grsec
INITRD initramfs-linux-grsec
APPEND root=UUID=...

Label fallback
MENU LABEL Linux grsec fallback
LINUX vmlinuz-grsec-fallback
INITRD initramfs-linux-grsec-fallback
APPEND root=UUID=...