linux-kernel - Re: [PATCH v4 03/12] powerpc/kexec_file: add helper functions for getting memory ranges

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Date:   Thu, 23 Jul 2020 19:12:05 -0300
From:   Thiago Jung Bauermann <bauerman@...ux.ibm.com>
To:     Hari Bathini <hbathini@...ux.ibm.com>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Pingfan Liu <piliu@...hat.com>,
        Kexec-ml <kexec@...ts.infradead.org>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Nayna Jain <nayna@...ux.ibm.com>,
        Petr Tesarik <ptesarik@...e.cz>,
        Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
        Sourabh Jain <sourabhjain@...ux.ibm.com>,
        lkml <linux-kernel@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...abs.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        Dave Young <dyoung@...hat.com>, Vivek Goyal <vgoyal@...hat.com>
Subject: Re: [PATCH v4 03/12] powerpc/kexec_file: add helper functions for getting memory ranges


Hari Bathini <hbathini@...ux.ibm.com> writes:

> 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@...ux.ibm.com>
> Tested-by: Pingfan Liu <piliu@...hat.com>

Just one comment below, but regardless:

Reviewed-by: Thiago Jung Bauermann <bauerman@...ux.ibm.com>

> +/**
> + * add_htab_mem_range - Adds htab range to the given memory ranges list,
> + *                      if it exists
> + * @mem_ranges:         Range list to add the memory range to.
> + *
> + * Returns 0 on success, negative errno on error.
> + */
> +int add_htab_mem_range(struct crash_mem **mem_ranges)
> +{
> +	if (!htab_address)
> +		return 0;
> +
> +	return add_mem_range(mem_ranges, __pa(htab_address), htab_size_bytes);
> +}

I believe you need to surround this function with `#ifdef
CONFIG_PPC_BOOK3S_64` and `#endif` to match what is done in
<asm/kexec_ranges.h>.

--
Thiago Jung Bauermann
IBM Linux Technology Center