From: Miles Chen <miles.chen@mediatek.com>
To: Mike Rapoport <rppt@linux.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Matthias Brugger <matthias.bgg@gmail.com>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-mediatek@lists.infradead.org>, <wsd_upstream@mediatek.com>
Subject: Re: [PATCH] mm/memblock: export max_pfn for kernel modules
Date: Thu, 4 Jun 2020 11:39:46 +0800 [thread overview]
Message-ID: <1591241986.29475.18.camel@mtkswgap22> (raw)
In-Reply-To: <20200603170624.GA202648@linux.ibm.com>
On Wed, 2020-06-03 at 20:06 +0300, Mike Rapoport wrote:
> On Thu, Jun 04, 2020 at 12:11:32AM +0800, 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.
>
> You can use totalram_pages(), like e.g.
> drivers/media/platform/mtk-vpu/mtk_vpu.c:
>
> $ git grep -np totalram_pages drivers/medhttps://lkml.org/lkml/2020/5/30/123ia/
> drivers/media/platform/mtk-vpu/mtk_vpu.c=779=static int mtk_vpu_probe(struct platform_device *pdev)
> drivers/media/platform/mtk-vpu/mtk_vpu.c:861: vpu->enable_4GB = !!(totalram_pages() > (SZ_2G >> PAGE_SHIFT));
>
Thanks for the suggestion.
totalram_pages() works and I can follow this example.
Miles
>
> > Signed-off-by: Miles Chen <miles.chen@mediatek.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;
> > --
> > 2.18.0
>
prev parent reply other threads:[~2020-06-04 3:39 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-03 16:11 [PATCH] mm/memblock: export max_pfn for kernel modules Miles Chen
2020-06-03 16:16 ` David Hildenbrand
2020-06-04 3:39 ` Miles Chen
2020-06-03 17:06 ` Mike Rapoport
2020-06-04 3:39 ` Miles Chen [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1591241986.29475.18.camel@mtkswgap22 \
--to=miles.chen@mediatek.com \
--cc=akpm@linux-foundation.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mediatek@lists.infradead.org \
--cc=linux-mm@kvack.org \
--cc=matthias.bgg@gmail.com \
--cc=rppt@linux.ibm.com \
--cc=wsd_upstream@mediatek.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).