Re: [PATCH] makedumpfile/arm64: Add support for ARMv8.2-LPA (52-bit PA support)

From: Bhupesh Sharma <bhsharma@redhat.com>
To: Kazuhito Hagio <k-hagio@ab.jp.nec.com>
Cc: kexec mailing list <kexec@lists.infradead.org>
Subject: Re: [PATCH] makedumpfile/arm64: Add support for ARMv8.2-LPA (52-bit PA support)
Date: Sun, 17 Feb 2019 01:58:59 +0530	[thread overview]
Message-ID: <2618e46c-4406-e322-8d7d-4f11a8fa02ad@redhat.com> (raw)
In-Reply-To: <4AE2DC15AC0B8543882A74EA0D43DBEC035685CE@BPXM09GP.gisp.nec.co.jp>

Hi Kazu,

On 02/14/2019 10:33 PM, Kazuhito Hagio wrote:
> Hi Bhupesh,
> 
> -----Original Message-----
>>>> Yes, the ARMv8 simulator can support both ARMv8.2 LPA and LVA features
>>>> and I tested the above suggestion earlier also on the same and landed
>>>> into incorrect paddress calculation issues.
>>>>
>>>> Since the simulator is slow and its time taking to insert rebuilt
>>>> user-space components in the Linaro initramfs being used on the same, I
>>>> would suggest that we go ahead with the above code for now and later
>>>> when I have more results from the simulator/real hardware, I will send
>>>> out a follow-up patch (if needed) to fix the paddress calculation.
>>>
>>> Hmm, it theoretically needs __pte_to_phys(), right?
>>> So if you have an issue with it, there may be a bug somewhere
>>> and need to debug it. Do you have the detailed information?
>>
>> Its not very easy to get the detailed UART console logs from the
>> simulator, so it is hard to get all the debug logs from makedumpfile, so
>> I am trying debugging the issue via 'gdb' by adding it to the initramfs.
> 
> I don't know what environment the simulater is, but you cannot
> capture a vmcore with cp or something? then debug makedumpfile
> with it on a real arm64 machine. I usually do like this.
> 
>    # cp --sparse=always /proc/vmcore vmcore
> 
> I'm willing to debug it if you would send me the vmcore and vmlinux.

Yes, unfortunately its a very restrictive environment and I cannot get 
network to work on it at my end :(, so its not easy to test new kenrel + 
user-space changes and also to export vmcore or dump logs outside the 
simulator.

However, I was able to create a new simulator vm-image today with the 
required changes and test your suggestions.

Thanks for sharing your  inputs. Accordingly I have incorporated your 
suggestions and have sent a v2 patchset today, merging the LPA and LVA 
makedumpfile changes into a single patchset for easier review.

Please see the same here: 
<http://lists.infradead.org/pipermail/kexec/2019-February/022456.html>

Thanks,
Bhupesh

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