Re: [PATCH v3 3/3] printk: use the lockless ringbuffer

From: lijiang <lijiang@redhat.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Andrea Parri <parri.andrea@gmail.com>,
	Paul McKenney <paulmck@kernel.org>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	John Ogness <john.ogness@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
	Steven Rostedt <rostedt@goodmis.org>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v3 3/3] printk: use the lockless ringbuffer
Date: Sat, 4 Jul 2020 09:12:06 +0800	[thread overview]
Message-ID: <56266e04-56b2-41fa-fff1-c3437ddec929@redhat.com> (raw)
In-Reply-To: <20200702133110.GE14288@alley>

在 2020年07月02日 21:31, Petr Mladek 写道:
> On Thu 2020-07-02 17:43:22, lijiang wrote:
>> 在 2020年07月02日 17:02, John Ogness 写道:
>>> On 2020-07-02, lijiang <lijiang@redhat.com> wrote:
>>>> About the VMCOREINFO part, I made some tests based on the kernel patch
>>>> v3, the makedumpfile and crash-utility can work as expected with your
>>>> patch(userspace patch), but, unfortunately, the vmcore-dmesg(kexec-tools)
>>>> can't correctly read the printk ring buffer information, and get the
>>>> following error:
>>>>
>>>> "Missing the log_buf symbol"
>>>>
>>>> The kexec-tools(vmcore-dmesg) should also have a similar patch, just like
>>>> in the makedumpfile and crash-utility.
>>>
>>> Yes, a patch for this is needed (as well as for any other related
>>> software floating around the internet).
>>>
>>> I have no RFC patches for vmcore-dmesg. Looking at the code, I think it
>>> would be quite straight forward to port the makedumpfile patch. I will
>>
>> Yes, it should be a similar patch.
>>
>>> try to make some time for this.
>>>
>> That would be nice. Thank you, John Ogness.
>>
>>> I do not want to patch any other software for this. I think with 3
>>> examples (crash, makedumpfile, vmcore-dmesg), others should be able to
>>
>> It's good enough to have the patch for the makedumpfile, crash and vmcore-dmesg,
>> which can ensure the kdump(userspace) work well.
> 
> I agree that this three are the most important ones and should be
> enough.
> 
> Thanks a lot for working on it and testing it.
> 
My pleasure. I will test the vmcore-dmesg later.

Thanks.
Lianbo

> Best Regards,
> Petr
> 

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