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From: Mike Rapoport <rppt@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	Jonathan Corbet <corbet@lwn.net>,
	Matt Turner <mattst88@gmail.com>, Mike Rapoport <rppt@kernel.org>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Richard Henderson <rth@twiddle.net>,
	Vineet Gupta <vgupta@synopsys.com>,
	kexec@lists.infradead.org, linux-alpha@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-doc@vger.kernel.org, linux-ia64@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
	linux-mips@vger.kernel.org, linux-mm@kvack.org,
	linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
	linux-sh@vger.kernel.org, linux-snps-arc@lists.infradead.org,
	linux-xtensa@linux-xtensa.org, linuxppc-dev@lists.ozlabs.org,
	sparclinux@vger.kernel.org
Subject: [PATCH 2/9] arc: update comment about HIGHMEM implementation
Date: Wed,  2 Jun 2021 13:53:41 +0300	[thread overview]
Message-ID: <20210602105348.13387-3-rppt@kernel.org> (raw)
In-Reply-To: <20210602105348.13387-1-rppt@kernel.org>

From: Mike Rapoport <rppt@linux.ibm.com>

Arc does not use DISCONTIGMEM to implement high memory, update the comment
describing how high memory works to reflect this.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
 arch/arc/mm/init.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index e2ed355438c9..397a201adfe3 100644
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -139,16 +139,13 @@ void __init setup_arch_memory(void)
 
 #ifdef CONFIG_HIGHMEM
 	/*
-	 * Populate a new node with highmem
-	 *
 	 * On ARC (w/o PAE) HIGHMEM addresses are actually smaller (0 based)
-	 * than addresses in normal ala low memory (0x8000_0000 based).
+	 * than addresses in normal aka low memory (0x8000_0000 based).
 	 * Even with PAE, the huge peripheral space hole would waste a lot of
-	 * mem with single mem_map[]. This warrants a mem_map per region design.
-	 * Thus HIGHMEM on ARC is imlemented with DISCONTIGMEM.
-	 *
-	 * DISCONTIGMEM in turns requires multiple nodes. node 0 above is
-	 * populated with normal memory zone while node 1 only has highmem
+	 * mem with single contiguous mem_map[].
+	 * Thus when HIGHMEM on ARC is enabled the memory map corresponding
+	 * to the hole is freed and ARC specific version of pfn_valid()
+	 * handles the hole in the memory map.
 	 */
 #ifdef CONFIG_DISCONTIGMEM
 	node_set_online(1);
-- 
2.28.0


  parent reply	other threads:[~2021-06-02 10:54 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-02 10:53 [PATCH 0/9] Remove DISCINTIGMEM memory model Mike Rapoport
2021-06-02 10:53 ` [PATCH 1/9] alpha: remove DISCONTIGMEM and NUMA Mike Rapoport
2021-06-09 10:50   ` David Hildenbrand
2021-06-02 10:53 ` Mike Rapoport [this message]
2021-06-09 10:52   ` [PATCH 2/9] arc: update comment about HIGHMEM implementation David Hildenbrand
2021-06-02 10:53 ` [PATCH 3/9] arc: remove support for DISCONTIGMEM Mike Rapoport
2021-06-09 10:53   ` David Hildenbrand
2021-06-02 10:53 ` [PATCH 4/9] m68k: " Mike Rapoport
2021-06-02 11:25   ` Geert Uytterhoeven
2021-06-02 14:03     ` Mike Rapoport
2021-06-02 10:53 ` [PATCH 5/9] mm: remove CONFIG_DISCONTIGMEM Mike Rapoport
2021-06-09 10:55   ` David Hildenbrand
2021-06-02 10:53 ` [PATCH 6/9] arch, mm: remove stale mentions of DISCONIGMEM Mike Rapoport
2021-06-09 10:55   ` David Hildenbrand
2021-06-02 10:53 ` [PATCH 7/9] docs: remove description of DISCONTIGMEM Mike Rapoport
2021-06-09 10:56   ` David Hildenbrand
2021-06-02 10:53 ` [PATCH 8/9] mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA Mike Rapoport
2021-06-09 10:56   ` David Hildenbrand
2021-06-02 10:53 ` [PATCH 9/9] mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM Mike Rapoport
2021-06-09 10:58   ` David Hildenbrand

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