I have managed to get Kernel 3.18-rc7 to boot on my Odroid U3, but it is still very unstable..

Fedora release 21 (Twenty One)
Kernel 3.18.0-rc7 on an armv7l (ttySAC1)
rgodroid login:
$ uname -a
Linux rgodroid 3.18.0-rc7 #3 SMP PREEMPT Wed Dec 3 18:41:29 EST 2014 armv7l armv7l armv7l GNU/Linux

Sometimes the device will boot without detecting the USB-connected Ethernet port (smsc95xx), and at other times it will be detected – and nothing has been changed between boot attempts..

The system still ‘tombstones’ at irregular intervals:

[ 69.610957] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:97
[ 69.613715] in_atomic(): 1, irqs_disabled(): 128, pid: 79, name: mmcqd/0
[ 69.620379] Preemption disabled at:[< (null)>] (null)

[ 69.627151] CPU: 0 PID: 79 Comm: mmcqd/0 Tainted: G W 3.18.0-rc7 #3
[ 69.634463] [<c001991c>] (unwind_backtrace) from [<c00140d8>] (show_stack+0x20/0x24)
[ 69.642176] [<c00140d8>] (show_stack) from [<c06f7ec8>] (dump_stack+0x90/0xd0)
[ 69.649387] [<c06f7ec8>] (dump_stack) from [<c004f4e0>] (__might_sleep+0x16c/0x174)
[ 69.657019] [<c004f4e0>] (__might_sleep) from [<c06fc2b8>] (mutex_lock+0x2c/0x4c)
[ 69.664479] [<c06fc2b8>] (mutex_lock) from [<c055f1a8>] (clk_prepare_lock+0x7c/0x104)
[ 69.672291] [<c055f1a8>] (clk_prepare_lock) from [<c05611cc>] (clk_set_rate+0x24/0xdc)
[ 69.680189] [<c05611cc>] (clk_set_rate) from [<c05409c8>] (sdhci_cmu_set_clock+0x78/0x150)
[ 69.688446] [<c05409c8>] (sdhci_cmu_set_clock) from [<c053c3f4>] (sdhci_do_set_ios+0x148/0x63c)
[ 69.697116] [<c053c3f4>] (sdhci_do_set_ios) from [<c053c1fc>] (sdhci_set_ios+0x38/0x48)
[ 69.705107] [<c053c1fc>] (sdhci_set_ios) from [<c05288a0>] (__mmc_set_clock+0xd4/0x118)
[ 69.713093] [<c05288a0>] (__mmc_set_clock) from [<c0528950>] (mmc_ungate_clock+0x34/0x38)
[ 69.721251] [<c0528950>] (mmc_ungate_clock) from [<c052b9dc>] (mmc_host_clk_hold+0x5c/0xc0)
[ 69.729582] [<c052b9dc>] (mmc_host_clk_hold) from [<c0526af8>] (mmc_start_request+0x218/0x250)
[ 69.738174] [<c0526af8>] (mmc_start_request) from [<c052822c>] (mmc_start_req+0x2fc/0x388)
[ 69.746420] [<c052822c>] (mmc_start_req) from [<c05383d4>] (mmc_blk_issue_rw_rq+0x3f4/0xa6c)
[ 69.754840] [<c05383d4>] (mmc_blk_issue_rw_rq) from [<c0538e78>] (mmc_blk_issue_rq+0x42c/0x50c)
[ 69.763519] [<c0538e78>] (mmc_blk_issue_rq) from [<c0539f74>] (mmc_queue_thread+0xbc/0x168)
[ 69.771863] [<c0539f74>] (mmc_queue_thread) from [<c0048168>] (kthread+0xec/0xf4)
[ 69.779327] [<c0048168>] (kthread) from [<c000fa58>] (ret_from_fork+0x14/0x20)

And…  The most annoying thing is that the fan is running constantly!    I have pwm-fan configured in, but it appears to have no effect..

I will keep testing, and hopefully 3.19-rc will bring some improvements..    Patches for this device seem to be around, now, but appear to be slow in acceptance into the actual kernel.org kernel codebase..

Robert Gadsdon.   December 4, 2014.