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Subject: Re: [PATCH v3 3/3] printk: use the lockless ringbuffer
To:     John Ogness <john.ogness@linutronix.de>,
        Petr Mladek <pmladek@suse.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrea Parri <parri.andrea@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Paul McKenney <paulmck@kernel.org>, kexec@lists.infradead.org,
        linux-kernel@vger.kernel.org
References: <20200618144919.9806-1-john.ogness@linutronix.de>
 <20200618144919.9806-4-john.ogness@linutronix.de>
 <ba338fab-9e98-366b-8fd4-05d4daa14f6d@redhat.com>
 <87zh8imgs5.fsf@jogness.linutronix.de>
From:   lijiang <lijiang@redhat.com>
Message-ID: <585a6a1b-931c-1034-e2cc-da2c4381751e@redhat.com>
Date:   Thu, 2 Jul 2020 17:43:22 +0800
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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.

Thanks.
Lianbo

> implement the changes to their software without needing my help.
> 
> John Ogness
>