# cat /sys/devices/bone_capemgr.9/slots
 0: 54:PF---
 1: 55:PF---
 2: 56:PF---
 3: 57:PF---
 4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
 5: ff:P-O-- Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
 6: ff:P-O-L Override Board Name,00A0,Override Manuf,BB-SPI0DEV
# echo -6 > /sys/devices/bone_capemgr.9/slots
[   68.412963] Unable to handle kernel NULL pointer dereference at virtual address 0000001b
[   68.422400] pgd = df794000
[   68.425250] [0000001b] *pgd=9f5d0831, *pte=00000000, *ppte=00000000
[   68.431838] Internal error: Oops: 17 [#1] SMP THUMB2
[   68.437008] Modules linked in: ath9k_htc ath9k_common ath9k_hw ath mac80211 cfg80211 rfkill ip_tables x_tables ipv6 autofs4
[   68.448682] CPU: 0    Not tainted  (3.8.13 #1)
[   68.453320] PC is at omap_device_enable+0xc/0x48
[   68.458127] LR is at _od_runtime_resume+0xb/0x14
[   68.462941] pc : [<c001f1e8>]    lr : [<c001f22f>]    psr: a0000133
[   68.462941] sp : df7e3dd8  ip : 22222222  fp : df0af480
[   68.474902] r10: df4eda80  r9 : c003d0cd  r8 : df7e3e08
[   68.480341] r7 : 00000004  r6 : 00000002  r5 : c001f225  r4 : 00000000
[   68.487143] r3 : 0000000c  r2 : 00750074  r1 : df4eda80  r0 : df4eda00
[   68.493944] Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA Thumb  Segment user
[   68.501560] Control: 50c5387d  Table: 9f794019  DAC: 00000015
[   68.507552] Process bash (pid: 286, stack limit = 0xdf7e2240)
[   68.513536] Stack: (0xdf7e3dd8 to 0xdf7e4000)
[   68.529108] 3dc0:                                                       df4eda10 c001f22f
[   68.546295] 3de0: df4eda10 c01f6a0b c0624bd8 df4eda10 df0af410 c01f7311 22222222 00000000
[   68.564886] 3e00: 00000000 dead4ead ffffffff ffffffff df4edb1c df4eda10 00000004 df4eda80
[   68.580533] 3e20: 40000113 00200200 df623a88 c03a8d50 df302810 c01f7595 dcabbac0 df4eda10
[   68.599696] 3e40: c066ff60 c0667138 00000000 c01f1775 dcabbac0 df4eda44 df4eda10 c01f17e7
[   68.615678] 3e60: 00000000 df4eda10 df04643c c01f14df df4eda10 df0af400 df0af410 c01f0275
[   68.632603] 3e80: df4eda00 df0af400 00000000 c01f2719 df4eda00 c01f2885 dc86b240 c02c87b3
[   68.644342] 3ea0: 0000004d dc86b240 df623a50 df623a88 00100100 c02c8831 dcabbac0 00000000
[   68.655668] 3ec0: ffffffb0 df623a58 df623a50 df623aa0 df62a000 c02c8d47 df5d9c10 00000000
[   68.666759] 3ee0: df112e10 df7e3f80 df112e10 c01ff3c3 00000006 df302820 df5866d8 c0200319
[   68.677797] 3f00: c0686cc0 c036f1fb 22222222 22222222 22222222 c02002c5 df5866c0 df5866d8
[   68.689806] 3f20: df7e3f80 00000003 df112e18 c03a8d50 00000000 c01ef723 df307e08 c00cd74d
[   68.701759] 3f40: df5cb5c0 000d8408 00000003 df7e3f80 000d8408 00000003 00000000 c00942d7
[   68.713074] 3f60: df5cb5c0 000d8408 00000000 00000000 df5cb5c0 00000000 000d8408 c00944e3
[   68.724292] 3f80: 00000000 00000000 00000003 00000003 000d8408 b6eb0a80 00000004 c000c7e4
[   68.736831] 3fa0: df7e2000 c000c641 00000003 000d8408 00000001 000d8408 00000003 00000000
[   68.748402] 3fc0: 00000003 000d8408 b6eb0a80 00000004 00000003 00000003 000d8408 00000000
[   68.759534] 3fe0: 00000000 beb54964 b6decb2c b6e3f30c 600e0010 00000001 6c2f6269 00647261
[   68.768185] [<c001f1e8>] (omap_device_enable+0xc/0x48) from [<c001f22f>] (_od_runtime_resume+0xb/0x14)
[   68.777926] [<c001f22f>] (_od_runtime_resume+0xb/0x14) from [<c01f6a0b>] (__rpm_callback+0x23/0x40)
[   68.787619] [<c01f6a0b>] (__rpm_callback+0x23/0x40) from [<c01f7311>] (rpm_resume+0x24f/0x31a)
[   68.796638] [<c01f7311>] (rpm_resume+0x24f/0x31a) from [<c01f7595>] (__pm_runtime_resume+0x45/0x52)
[   68.806103] [<c01f7595>] (__pm_runtime_resume+0x45/0x52) from [<c01f1775>] (__device_release_driver+0x11/0x6e)
[   68.816554] [<c01f1775>] (__device_release_driver+0x11/0x6e) from [<c01f17e7>] (device_release_driver+0x15/0x1e)
[   68.827185] [<c01f17e7>] (device_release_driver+0x15/0x1e) from [<c01f14df>] (bus_remove_device+0x77/0x88)
[   68.837286] [<c01f14df>] (bus_remove_device+0x77/0x88) from [<c01f0275>] (device_del+0xa5/0xec)
[   68.846376] [<c01f0275>] (device_del+0xa5/0xec) from [<c01f2719>] (platform_device_del+0xd/0x30)
[   68.855561] [<c01f2719>] (platform_device_del+0xd/0x30) from [<c01f2885>] (platform_device_unregister+0x9/0x12)
[   68.866115] [<c01f2885>] (platform_device_unregister+0x9/0x12) from [<c02c87b3>] (of_overlay_device_entry_change.isra.1+0x8f/0xd8)
[   68.878383] [<c02c87b3>] (of_overlay_device_entry_change.isra.1+0x8f/0xd8) from [<c02c8831>] (of_overlay_revert_one+0x35/0x148)
[   68.890452] [<c02c8831>] (of_overlay_revert_one+0x35/0x148) from [<c02c8d47>] (of_overlay_revert+0x2b/0x46)
[   68.900658] [<c02c8d47>] (of_overlay_revert+0x2b/0x46) from [<c01ff3c3>] (bone_capemgr_remove_slot_no_lock+0x27/0x94)
[   68.911744] [<c01ff3c3>] (bone_capemgr_remove_slot_no_lock+0x27/0x94) from [<c0200319>] (slots_store+0x55/0x25c)
[   68.922389] [<c0200319>] (slots_store+0x55/0x25c) from [<c01ef723>] (dev_attr_store+0xb/0x12)
[   68.931312] [<c01ef723>] (dev_attr_store+0xb/0x12) from [<c00cd74d>] (sysfs_write_file+0x9d/0xd8)
[   68.940612] [<c00cd74d>] (sysfs_write_file+0x9d/0xd8) from [<c00942d7>] (vfs_write+0x63/0x104)
[   68.949618] [<c00942d7>] (vfs_write+0x63/0x104) from [<c00944e3>] (sys_write+0x27/0x44)
[   68.957992] [<c00944e3>] (sys_write+0x27/0x44) from [<c000c641>] (ret_fast_syscall+0x1/0x46)
[   68.968274] Code: f8d0 41c8 e000 4604 (7ee3) 2b01
[   68.973330] ---[ end trace 32fdb1e740bf2f6c ]---