linux-kernel - Re: [PATCH v2 2/7] MIPS: csrc-r4k: Apply verification clocksource flags

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Message-ID: <62e8056b-6a6c-42d1-89f6-7306bb2a528b@roeck-us.net>
Date: Mon, 5 Aug 2024 22:13:25 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Jiaxun Yang <jiaxun.yang@...goat.com>
Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
 Serge Semin <fancer.lancer@...il.com>,
 Daniel Lezcano <daniel.lezcano@...aro.org>,
 Thomas Gleixner <tglx@...utronix.de>, "Maciej W. Rozycki"
 <macro@...am.me.uk>, "linux-mips@...r.kernel.org"
 <linux-mips@...r.kernel.org>, linux-kernel@...r.kernel.org,
 regressions@...ts.linux.dev
Subject: Re: [PATCH v2 2/7] MIPS: csrc-r4k: Apply verification clocksource
 flags

On 8/5/24 22:06, Jiaxun Yang wrote:
> 
> 
> 在2024年8月6日八月 下午12:09，Guenter Roeck写道：
>> Hi,
>>
>> On Wed, Jun 12, 2024 at 09:54:29AM +0100, Jiaxun Yang wrote:
>>> CP0 counter suffers from various problems like SMP sync,
>>> behaviour on wait.
>>>
>>> Set CLOCK_SOURCE_MUST_VERIFY and CLOCK_SOURCE_VERIFY_PERCPU,
>>> as what x86 did to TSC, to let kernel test it before use.
>>>
>>> Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
> 
> Hi Guenter,
> 
> Thanks for the report, it makes no sense to me though....
> 
> I can't reproduce it with QEMU git master, do you mind specifying your QEMU
> version for me? Also is it possible to have a copy of dmesg when failure happens.
> 

I currently use v9.0.2. I'll try with some other versions tomorrow.
A complete log is at
https://kerneltests.org/builders/qemu-mips64-master/builds/241/steps/qemubuildcommand/logs/stdio

Are you trying to instantiate an e1000 (or a variant of it) ? So far
I have only seen the problem with that controller. There is no specific
error message, the network interface just doesn't get an IP address.

Thanks,
Guenter

> If I'm unable to resolve it in a couple of days, I'll send a patch to revert this change.
> 
> Thanks
> 
>>
>> With this patch in the mainline kernel, about one in five qemu
>> boot attempts with e1000 Ethernet controller fail to activate
>> the network interface (specifically, the dhcp client is unable to
>> get an IP address for the interface). Bisect log is attached below.
>>
>> For reference, here is an example command line.
>>
>> qemu-system-mips64 -kernel vmlinux -M malta -cpu 5KEc \
>> 	-initrd rootfs-n32.cpio \
>> 	-device e1000,netdev=net0 -netdev user,id=net0 \
>> 	-vga cirrus -no-reboot -m 256 \
>> 	--append "rdinit=/sbin/init mem=256M console=ttyS0 console=tty " \
>> 	-nographic
>>
>> Reverting this patch fixes the probem.
>>
>> Thanks,
>> Guenter
>>
>> ---
>> # bad: [de9c2c66ad8e787abec7c9d7eff4f8c3cdd28aed] Linux 6.11-rc2
>> # good: [0c3836482481200ead7b416ca80c68a29cfdaabd] Linux 6.10
>> git bisect start 'HEAD' 'v6.10'
>> # good: [280e36f0d5b997173d014c07484c03a7f7750668] nsfs: use cleanup
>> guard
>> git bisect good 280e36f0d5b997173d014c07484c03a7f7750668
>> # good: [a4f9285520584977127946a22eab2adfbc87d1bf] Merge tag
>> 'clk-for-linus' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux
>> git bisect good a4f9285520584977127946a22eab2adfbc87d1bf
>> # bad: [8e313211f7d46d42b6aa7601b972fe89dcc4a076] Merge tag
>> 'pinctrl-v6.11-1' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl
>> git bisect bad 8e313211f7d46d42b6aa7601b972fe89dcc4a076
>> # good: [acc5965b9ff8a1889f5b51466562896d59c6e1b9] Merge tag
>> 'char-misc-6.11-rc1' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
>> git bisect good acc5965b9ff8a1889f5b51466562896d59c6e1b9
>> # bad: [d2be38b9a5514dbc7dc0c96a2a7f619fcddce00d] Merge tag 'mips_6.11'
>> of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux
>> git bisect bad d2be38b9a5514dbc7dc0c96a2a7f619fcddce00d
>> # good: [45659274e60864f9acabba844468e405362bdc8c] Merge branch
>> 'pci/misc'
>> git bisect good 45659274e60864f9acabba844468e405362bdc8c
>> # good: [8e5c0abfa02d85b9cd2419567ad2d73ed8fe4b74] Merge tag
>> 'input-for-v6.11-rc0' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
>> git bisect good 8e5c0abfa02d85b9cd2419567ad2d73ed8fe4b74
>> # good: [3c3ff7be9729959699eb6cbc7fd7303566d74069] Merge tag
>> 'powerpc-6.11-1' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
>> git bisect good 3c3ff7be9729959699eb6cbc7fd7303566d74069
>> # good: [3de96d810ffd712b7ad2bd764c1390fac2436551] dt-bindings: mips:
>> brcm: Document brcm,bmips-cbr-reg property
>> git bisect good 3de96d810ffd712b7ad2bd764c1390fac2436551
>> # bad: [9c7a86c935074525f24cc20e78a7d5150e4600e3] MIPS: lantiq: improve
>> USB initialization
>> git bisect bad 9c7a86c935074525f24cc20e78a7d5150e4600e3
>> # bad: [580724fce27f2b71b3e4d58bbe6d83b671929b33] MIPS: sync-r4k:
>> Rework based on x86 tsc_sync
>> git bisect bad 580724fce27f2b71b3e4d58bbe6d83b671929b33
>> # good: [c171186c177970d3ec22dd814f2693f1f7fc1e7d] MIPS: csrc-r4k:
>> Refine rating computation
>> git bisect good c171186c177970d3ec22dd814f2693f1f7fc1e7d
>> # bad: [426fa8e4fe7bb914b5977cbce453a9926bf5b2e6] MIPS: csrc-r4k:
>> Select HAVE_UNSTABLE_SCHED_CLOCK if SMP && 64BIT
>> git bisect bad 426fa8e4fe7bb914b5977cbce453a9926bf5b2e6
>> # bad: [7190401fc56fb5f02ee3d04476778ab000bbaf32] MIPS: csrc-r4k: Apply
>> verification clocksource flags
>> git bisect bad 7190401fc56fb5f02ee3d04476778ab000bbaf32
>> # first bad commit: [7190401fc56fb5f02ee3d04476778ab000bbaf32] MIPS:
>> csrc-r4k: Apply verification clocksource flags
>