On 07/29/2015 23:53, Kevin Oberman wrote:> On Wed, Jul 29, 2015 at 5:58 AM, Claude Buisson <clbuisson at
orange.fr> wrote:
>
>> On 07/26/2015 00:54, Kevin Oberman wrote:
>>
>>> John,
>>>
>>> I'm concerned that two issues may be getting conflated.
>>>
>>> The issue I thought we were looking at was the failure of some
systems
>>> (T520, X220, T430) to resume after a number of PCI enhancements
were
>>> MFCed.
>>> This is completely unrelated to the USB issue I was experiencing
when
>>> trying to test the problem on HEAD. The more I think about it, the
more I
>>> think that the USB "issue" is just how things need to
work.
>>>
>>> Specifically, if you are booting a full, multi-user system from a
USB
>>> connected drive, suspending and resuming will leave the system in
an
>>> untenable condition that will force a panic. At least I don't
see how the
>>> OS can determine that the disk present on resume is unchanged from
that
>>> present when the system was suspended. Modern disk IDs greatly
improve the
>>> situation, but I am unaware of any way to be sure that a removable
drive
>>> (such as a USB) has not been removed and plugged into some other
system
>>> that might have written to it. My knowledge of such things is very
dated,
>>> going back to my days doing kernel programming about 25-30 year ago
on
>>> VMS,
>>> so someone may have resolved the issue, but I don't understand
exactly
>>> how.
>>> I guess that the risk might be low enough to just go ahead and pray
that
>>> nobody did something really, really stupid like unplugging the
drive,
>>> plugging it in elsewhere, and writing to it.
>>>
>>> The real issue is just resuming the system after r281874 was MFCed
as a
>>> part of 284034. No USB connected file systems are involved. I m
happy to
>>> see that it has been reverted for 10.2, but clearly, these changes
are
>>> needed down the line and I hope the issue can be resolved well
before
>>> 11.0.
>>> (This assumes a 10.3 before 11.0 happens next year.)
>>>
>>>
>> I have done some tests on my T530 at r285668 and had some (good and
bad)
>> surprises:
>>
>> 0) historically i915kms+drm2 could not be loaded by loader.conf without
>> locking the machine, but needed to be loaded by rc.conf (kld_list). Now
>> these modules can be loaded by loader.conf.
>>
>> 1) resume does not work with a non patched kernel, but works when the
>> MFC of r281874 is reverted (i.e. r285863 applied) - in console mode
(vt)
>> and X.org.
>>
>> 2) and now is my bad surprise: when i915kms+drm2+iic*+kbdmux are not
>> loaded at all, suspend works (in console mode of course), but not
>> resume, both with the nonpatched and the patched kernel. After resume
>> the screen keeps being black, but the system can be logged to with ssh,
>> but cannot be powered off nor rebooted from another system. Furthermore
>> the log shows unidentified _USB_ devices at resume (which never
appeared
>> in any log before):
>>
>> Jul 29 12:28:12 watson devd: Executing '/etc/rc.suspend acpi
0x03'
>> Jul 29 12:28:12 watson acpi: suspend at 20150729 12:28:12
>> Jul 29 12:28:37 watson kernel: uhub0: at usbus0, port 1, addr 1
>> (disconnected)
>> Jul 29 12:28:37 watson kernel: uhub1: at usbus1, port 1, addr 1
>> (disconnected)
>> Jul 29 12:28:37 watson kernel: ugen1.2: <vendor 0x8087> at usbus1
>> (disconnected)
>> Jul 29 12:28:37 watson kernel: uhub4: at uhub1, port 1, addr 2
>> (disconnected)
>> Jul 29 12:28:37 watson kernel: ugen1.3: <Chicony Electronics Co.,
Ltd.>
>> at usbus1 (disconnected)
>> Jul 29 12:28:37 watson kernel: uhub2: at usbus2, port 1, addr 1
>> (disconnected)
>> Jul 29 12:28:37 watson kernel: ugen2.2: <vendor 0x8087> at usbus2
>> (disconnected)
>> Jul 29 12:28:37 watson kernel: uhub3: at uhub2, port 1, addr 2
>> (disconnected)
>> Jul 29 12:28:37 watson kernel: ugen2.3: <Logitech> at usbus2
(disconnected)
>> Jul 29 12:28:37 watson kernel: ums0: at uhub3, port 5, addr 3
>> (disconnected)
>> Jul 29 12:28:37 watson kernel: acpi0: cleared fixed power button status
>> Jul 29 12:28:37 watson kernel: em0: link state changed to DOWN
>> Jul 29 12:28:37 watson kernel: xhci0: Port routing mask set to
0xffffffff
>> Jul 29 12:28:37 watson kernel: uhub0: <0x8086 XHCI root HUB, class
9/0,
>> rev 3.00/1.00, addr 1> on usbus0
>> Jul 29 12:28:37 watson kernel: uhub1: <Intel EHCI root HUB, class
9/0,
>> rev 2.00/1.00, addr 1> on usbus2
>> Jul 29 12:28:37 watson kernel: uhub2: <Intel EHCI root HUB, class
9/0,
>> rev 2.00/1.00, addr 1> on usbus1
>> Jul 29 12:28:38 watson kernel: uhub0: 8 ports with 8 removable, self
>> powered
>> Jul 29 12:28:37 watson devd: Executing '/etc/rc.resume acpi
0x03'
>> Jul 29 12:28:38 watson acpi: resumed at 20150729 12:28:38
>> Jul 29 12:28:38 watson kernel: uhub2: 3 ports with 3 removable, self
>> powered
>> Jul 29 12:28:38 watson kernel: uhub1: 3 ports with 3 removable, self
>> powered
>> Jul 29 12:28:38 watson kernel: em0: link state changed to UP
>> Jul 29 12:28:38 watson devd: Executing '/etc/rc.d/dhclient
quietstart em0'
>> Jul 29 12:28:39 watson kernel: ugen2.2: <vendor 0x8087> at usbus2
>> Jul 29 12:28:39 watson kernel: uhub3: <vendor 0x8087 product 0x0024,
>> class 9/0, rev 2.00/0.00, addr 2> on usbus2
>> Jul 29 12:28:39 watson kernel: ugen1.2: <vendor 0x8087> at usbus1
>> Jul 29 12:28:39 watson kernel: uhub4: <vendor 0x8087 product 0x0024,
>> class 9/0, rev 2.00/0.00, addr 2> on usbus1
>> Jul 29 12:28:40 watson kernel: uhub4: 6 ports with 6 removable, self
>> powered
>> Jul 29 12:28:41 watson kernel: uhub3: 8 ports with 8 removable, self
>> powered
>> Jul 29 12:28:41 watson kernel: ugen1.3: <Chicony Electronics Co.,
Ltd.>
>> at usbus1
>> Jul 29 12:28:41 watson devd: Executing 'logger Unknown USB device:
>> vendor 0x04f2 product 0xb2ea bus uhub4'
>> Jul 29 12:28:41 watson root: Unknown USB device: vendor 0x04f2 product
>> 0xb2ea bus uhub4
>> Jul 29 12:28:41 watson devd: Executing 'logger Unknown USB device:
>> vendor 0x04f2 product 0xb2ea bus uhub4'
>> Jul 29 12:28:41 watson root: Unknown USB device: vendor 0x04f2 product
>> 0xb2ea bus uhub4
>> Jul 29 12:28:41 watson kernel: ugen2.3: <Logitech> at usbus2
>> Jul 29 12:28:41 watson devd: Executing 'logger Unknown USB device:
>> vendor 0x046d product 0xc52b bus uhub3'
>> Jul 29 12:28:41 watson root: Unknown USB device: vendor 0x046d product
>> 0xc52b bus uhub3
>> Jul 29 12:28:41 watson kernel: ums0: <Logitech USB Receiver, class
0/0,
>> rev 2.00/24.00, addr 3> on usbus2
>> Jul 29 12:28:41 watson kernel: ums0: 16 buttons and [XYZT] coordinates
ID=2
>> Jul 29 12:28:41 watson devd: Executing 'logger Unknown USB device:
>> vendor 0x046d product 0xc52b bus uhub3'
>> Jul 29 12:28:41 watson root: Unknown USB device: vendor 0x046d product
>> 0xc52b bus uhub3
>>
>> I dare say that there is some mess somewhere..
>>
>> 4) last minute tests: I get the same resume problem as 3) supra when
>> booting from a USB stick with a 11-CURRENT snapshot, both
>> 20150330-r28086 and 20150722-r285794 (and cannot obtain anything useful
>> from /var/log/messages)
>>
>> Claude Buisson
>>
>>
> I am a bit confused by several things.
>
> 0) Yes, I understand that i915 can be loaded at boot time without the
> display going away, but I am still unclear on why people do this (or force
> it's loading in any other way). IIRC, before the i915 code was
committed to
> HEAD, the kernel module has auto-loaded when X started. I just
"startx". It
> also loads fine if you use a display manager (gdm, xdm, kdm... )to start X.
>
> Is there some special reason that you need the module loaded prior to X
> starting?
>
I do not like having console display sizes varying with the direction of
winds, phase of the moon, etc.. So I try to load the module as soon as
possible at boot, and find it in the same state when switching back from
X to console mode.
Any one is permitted to have personal preferences ?
> 1) Here the confusion starts. You say that resume works as of r285863 after
> saying that it does not work with an non-patched kernel. These statement
> seem self-contradictory. Are you saying that after r285863 that other
> patches are required? Or are you talking about a distributed binary kernel
> as opposed to STABLE, in which case, yes, you will need to wait until next
> week for RC2.
>
I say that:
resume does not work on my T530 at r285668, and works on my T530 at
r285668+r285863 i.e. the same system patched with r285863, with
I915kms,drm2,.. modules preloaded at boot.
> 2) Yes, I was under the impression that vt(4) would allow suspend/resume to
> work vtys, but I have also found that to not be the case. I just have not
> had the time or interest to pursue the issue or even do any real testing.
> (In other words, I really don't care too much.)
>
I care..
And my observation seems to imply that resume with vt does not work (at
least on this system) with vt simply in vga mode. Next experiment will
be to build a kernel witk syscons.
But I would be happy to get an explanation of the detection of
nonexistent/unknown USB devices at resume, without any physical change.
> 4) This refers to "3)", but I only see 0, 1, 2, and 4. Where did
3 go?
>
My error: replace 4) by 3) and 3) by 2) !
> Look back in this thread for discussion of the issue. Simply stated, no
> system can resume successfully when booted from a USB drive. The problem is
> that, on suspend all USB devices are removed from the system and on resume
> they are re-created, but there is no way to assure that a device that is
> present when the system is essentially "OFF" is consistent after
it is
> re-connected. This problem was one that I faced 30 years ago with long dead
> operating systems (RSX-11D, RSX11-M and IAS) and it has not been resolved
> in all of those years. Thanks to the fact that all useful drives are now
> "smart", there is hope that this can be resolved in some way. It
is
> certainly possible to confirm that the same physical drive is available on
> resume, but it might be on a different device name, so this will likely use
> gptid or some similar technique to do so.
>
> Even then, how can you tell if the drive was moved to another system,
> written to, and returned to the suspended system before it was restored?
> Just don't expect it any time soon. It's a really hard problem that
used to
> be an impossible one. I suspect that it will probably always be at least a
> bit unsafe, as it is today with removable SATA drives. (I can suspend my
> system, unplug the system disk (on the second spindle on my T520), plug it
> into another system, modify its contents, and put it back, and resume to a
> likely disaster. USB just makes this disaster easier.
> --
You are saying that resume cannot work when booting from an USB key,
even without any physical change intervening between suspend and resume.
So this part of my experiment cannot succeed.
I take note
> Kevin Oberman, Network Engineer, Retired
> E-mail: rkoberman at gmail.com
> PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683
Claude Buisson, another "Network Engineer, Retired" ;-)