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Subject: Re: [PATCH v4 03/12] powerpc/kexec_file: add helper functions for
 getting memory ranges
From:   Hari Bathini <hbathini@linux.ibm.com>
To:     Michael Ellerman <mpe@ellerman.id.au>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     Pingfan Liu <piliu@redhat.com>,
        Kexec-ml <kexec@lists.infradead.org>,
        Nayna Jain <nayna@linux.ibm.com>,
        Petr Tesarik <ptesarik@suse.cz>,
        Mahesh J Salgaonkar <mahesh@linux.ibm.com>,
        Mimi Zohar <zohar@linux.ibm.com>,
        lkml <linux-kernel@vger.kernel.org>,
        linuxppc-dev <linuxppc-dev@ozlabs.org>,
        Sourabh Jain <sourabhjain@linux.ibm.com>,
        Vivek Goyal <vgoyal@redhat.com>,
        Dave Young <dyoung@redhat.com>,
        Thiago Jung Bauermann <bauerman@linux.ibm.com>,
        Eric Biederman <ebiederm@xmission.com>
References: <159524918900.20855.17709718993097359220.stgit@hbathini.in.ibm.com>
 <159524946347.20855.15784642736087777919.stgit@hbathini.in.ibm.com>
Message-ID: <d6b0b134-f681-cc56-d0c1-dd581d518263@linux.ibm.com>
Date:   Mon, 20 Jul 2020 18:29:15 +0530
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On 20/07/20 6:21 pm, Hari Bathini wrote:
> In kexec case, the kernel to be loaded uses the same memory layout as
> the running kernel. So, passing on the DT of the running kernel would
> be good enough.
> 
> But in case of kdump, different memory ranges are needed to manage
> loading the kdump kernel, booting into it and exporting the elfcore
> of the crashing kernel. The ranges are exclude memory ranges, usable
> memory ranges, reserved memory ranges and crash memory ranges.
> 
> Exclude memory ranges specify the list of memory ranges to avoid while
> loading kdump segments. Usable memory ranges list the memory ranges
> that could be used for booting kdump kernel. Reserved memory ranges
> list the memory regions for the loading kernel's reserve map. Crash
> memory ranges list the memory ranges to be exported as the crashing
> kernel's elfcore.
> 
> Add helper functions for setting up the above mentioned memory ranges.
> This helpers facilitate in understanding the subsequent changes better
> and make it easy to setup the different memory ranges listed above, as
> and when appropriate.
> 
> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
> Tested-by: Pingfan Liu <piliu@redhat.com>
> ---

> 
> v3 -> v4:
> * Unchanged. Added Reviewed-by tag from Thiago.
> 
> v2 -> v3:
> * Unchanged. Added Acked-by & Tested-by tags from Dave & Pingfan.
> 
> v1 -> v2:
> * Introduced arch_kexec_locate_mem_hole() for override and dropped
>   weak arch_kexec_add_buffer().
> * Dropped __weak identifier for arch overridable functions.
> * Fixed the missing declaration for arch_kimage_file_post_load_cleanup()
>   reported by lkp. lkp report for reference:
>     - https://lore.kernel.org/patchwork/patch/1264418/

Sorry, copy-paste error. The patch version changelog is as follows:

v3 -> v4:
* Updated sort_memory_ranges() function to reuse sort() from lib/sort.c
  and addressed other review comments from Thiago.

v2 -> v3:
* Unchanged. Added Tested-by tag from Pingfan.

v1 -> v2:
* Added an option to merge ranges while sorting to minimize reallocations
  for memory ranges list.
* Dropped within_crashkernel option for add_opal_mem_range() &
  add_rtas_mem_range() as it is not really needed.


Thanks
Hari