kernel panic while building SDIO driver

Stanislav Sedov stas at
Sun Apr 15 17:54:08 UTC 2018

> On Apr 15, 2018, at 8:01 AM, Udit agarwal <dev.madaari at> wrote:
> Hi,
> I have been trying to build the kernel (for BBB) invoking SDIO driver from
> FreeBSD latest src tree using BEAGLEBONE-MMCCAM kernconf file(Yes, I added
> that file manually). I seems like the kernel panics due to sleep
> lock(complete logs:
> )
> mmc_dev_async(async_code=0x20, path_id=1, target_id=0, lun_id=0
> Got AC_PATH_REGISTERED -- whatever...
> mmc_dev_async(async_code=0x20, path_id=1, target_id=ffffffff,
> lun_id=ffffffff
> usbus0: 480Mbps High Speed USB v2.0
> usbus1: 480Mbps High Speed USB v2.0
> (noperiph:sdhci_slot0:0:-1:ffffffff): XPT_SCAN_{BUS,TGT,LUN}
> Kernel page fault with the following non-sleepable locks held:
> exclusive sleep mutex CAM device lock (CAM device lock) r = 0 (0xc30e1464)
> lock2
> stack backtrace:
> Fatal kernel mode data abort: 'Translation Fault (L1)' on read
> trapframe: 0xd0dc0ac0
> FSR=00000005, FAR=00000010, spsr=60000013
> r0 =00000061, r1 =00000188, r2 =d0dc0a8c, r3 =60000013
> r4 =c30e0000, r5 =c30dec40, r6 =00000000, r7 =d0dc0b68
> r8 =c086f528, r9 =c068f050, r10=00000000, r11=d0dc0d10
> r12=00000062, ssp=d0dc0b50, slr=c002b77c, pc =c002b5c0
> [ thread pid 4 tid 100048 ]
> Stopped at mmc_action+0x94: ldr r6, [r6, #0x010]
> db>
> Any idea how to resolve this?

It actually panicked on read fault (see L1 translation failure) on trying to read the address which isn’t mapped.  From the obstruction printed, it appears to be r6, which is 0x0 — most likely a NULL pointer dereference in the code.  What is at mmc_action+0x95 in your kernel?


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