linux-kernel - Re: [PATCH] mm/memblock: export max

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Date:   Wed, 3 Jun 2020 18:16:47 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Miles Chen <miles.chen@...iatek.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, wsd_upstream@...iatek.com
Subject: Re: [PATCH] mm/memblock: export max_pfn for kernel modules

On 03.06.20 18:11, Miles Chen wrote:
> max_pfn is uesd to get the highest pfn in the system. Drivers like
> drivers/iommu/mtk_iommu.c checks max_pfn to see if it should enable
> its "4GB mode".
> 
> This patch exports the max_pfn symbol, so we can build the driver as
> a kernel module.

Please add that change to the respective user patch (and cc MM-people
for that patch), so we have the actual user right along the change and
can figure out if this is the right thing to do.

> 
> Signed-off-by: Miles Chen <miles.chen@...iatek.com>
> ---
>  mm/memblock.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/memblock.c b/mm/memblock.c
> index c79ba6f9920c..3b2b21ecebb6 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -99,6 +99,7 @@ EXPORT_SYMBOL(contig_page_data);
>  unsigned long max_low_pfn;
>  unsigned long min_low_pfn;
>  unsigned long max_pfn;
> +EXPORT_SYMBOL(max_pfn);
>  unsigned long long max_possible_pfn;
>  
>  static struct memblock_region memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
> 


-- 
Thanks,

David / dhildenb