Tried updating the Raspberry Pi-s (Classic model B and Pi2) to Kernel 4.0, from https://github.com/raspberrypi/linux/tree/rpi-4.0.y, and my first attempt was – it seems – too soon, as the Classic Pi (armv6) failed to boot at all, and the Pi2 (armv7) only booted as far as:

.............
bcm2708_dma: DMA manager at f3007000
bcm2708_gpio: bcm2708_gpio_probe 80625490
vc-mem: phys_addr:0x00000000 mem_base=0x3dc00000 mem_size:0x3f000000(1008 MiB)
futex hash table entries: 1024 (order: 4, 65536 bytes)
audit: initializing netlink subsys (disabled)
audit: type=2000 audit(0.778:1): initialized
VFS: Disk quotas dquot_6.5.2
VFS: Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
Block layer SCSI generic (bsg) driver version 0.4 loaded (major 252)
io scheduler noop registered
io scheduler deadline registered (default)
io scheduler cfq registered
BCM2708FB: allocated DMA memory 76c00000
BCM2708FB: allocated DMA channel 0 @ f3007000
<< HANG >>

Later, I noticed some more commits to the tree, and re-downloaded the ‘later’ version…

# git clone -b rpi-4.0.y --single-branch https://github.com/raspberrypi/linux

This time, the Classic Pi booted successfully:

Pidora release 2014 (Raspberry Pi Fedora Remix)
Kernel 4.0.0 on an armv6l (ttyAMA0)
........
]# uname -a
Linux rgpi 4.0.0 #1 PREEMPT Mon Apr 13 21:34:08 PDT 2015 armv6l armv6l armv6l GNU/Linux

– but the Pi2 still hung during boot, at the same point as before..

So…  I will have to wait for more changes to the tree!

Robert Gadsdon.   April 13, 2015