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Date:      Thu, 12 Sep 2013 09:44:14 -0600
From:      Warner Losh <imp@bsdimp.com>
To:        Ian Lepore <ian@FreeBSD.org>
Cc:        "freebsd-arm@freebsd.org" <freebsd-arm@FreeBSD.org>
Subject:   Re: Panic mounting root on BeagleBone Black
Message-ID:  <F85C2A12-21DC-41C6-9037-15AFD0B1AD7E@bsdimp.com>
In-Reply-To: <1378997738.1111.631.camel@revolution.hippie.lan>
References:  <47E403AE-01A2-4AC8-8028-41F0298FAC3E@freebsd.org> <1378997738.1111.631.camel@revolution.hippie.lan>

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On Sep 12, 2013, at 8:55 AM, Ian Lepore wrote:

> On Wed, 2013-09-11 at 06:43 -0700, Tim Kientzle wrote:
>> Just built a new image for BBB from SVN r255438.
>>=20
>> At the second boot, I got this:
>> =10=10
>> Mounting local file systems:.
>> mmcsd0: Error indicated: 1 Timeout
>> g_vfs_done():mmcsd0s2a[READ(offset=3D2016903168, length=3D4096)]error =
=3D 5
>> vnode_pager_getpages: I/O read error
>> vm_fault: pager read error, pid 126 (ps)
>> mmcsd0: Error indicated: 1 Timeout
>> g_vfs_done():mmcsd0s2a[READ(offset=3D131072, length=3D32768)]error =3D =
5
>> sdhci_ti0-slot0: Got data interrupt 0x00000010, but there is no =
active command.
>> sdhci_ti0-slot0: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D REGISTER =
DUMP =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> sdhci_ti0-slot0: Sys addr: 0x00000000 | Version:  0x00003101
>> sdhci_ti0-slot0: Blk size: 0x00000200 | Blk cnt:  0x00000010
>> sdhci_ti0-slot0: Argument: 0x0024679e | Trn mode: 0x0000193a
>> sdhci_ti0-slot0: Present:  0x01f70000 | Host ctl: 0x00000006
>> sdhci_ti0-slot0: Power:    0x0000000d | Blk gap:  0x00000000
>> sdhci_ti0-slot0: Wake-up:  0x00000000 | Clock:    0x00000007
>> sdhci_ti0-slot0: Timeout:  0x0000000d | Int stat: 0x00000000
>> sdhci_ti0-slot0: Int enab: 0x017f00fb | Sig enab: 0x017f00fb
>> sdhci_ti0-slot0: AC12 err: 0x00000000 | Slot int: 0x00000000
>> sdhci_ti0-slot0: Caps:     0x06e10080 | Max curr: 0x00000000
>> sdhci_ti0-slot0: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=

>>=20
>> =85. few more similar messages, then =85.
>>=20
>> mmcsd0: Error indicated: 1 Timeout
>> g_vfs_done():mmcsd0s2a[WRITE(offset=3D20808192, length=3D512)]error =3D=
 5
>> g_vfs_done():mmcsd0s2a[WRITE(offset=3D1276346368, length=3D24576)]error=
 =3D 5
>> panic: brelse: inappropriate B_PAGING or B_CLUSTER bp 0xcd148778
>> [bt snipped]
>>=20
>=20
> This was a single occurance, right?  Like you're not dead in the water
> or anything?
>=20
> There's insanity in that info... the register dump shows a multi-block
> write (8kbytes) was set up, but the command that timed out was a read.
> If a prior write had timed out why isn't there a g_vfs_done() error
> logged for it?
>=20
> I think what we really need is some better error recovery in the mmc =
and
> sd layers.  Retrying a failed IO is cheap and easy.  More complex
> recovery is possible too (power cycling and re-intializing the card
> and/or controller).  But that has its own difficulties -- what if the
> nature of the problem was that the user swapped cards? -- you don't =
want
> to retry a write under those conditions.

I'd disagree with this...  Retrying often is the wrong thing to do. If =
the write didn't work the first time, why would it work the second? =
Looks like a programming bug here in controlling the sdhci controller =
since we got errors, then we got an interrupt with no pending commands. =
This suggests that our timeout isn't quite right...

Warner




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