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Message-Id: <20150210212030.665EC267@viggo.jf.intel.com>
Date: Tue, 10 Feb 2015 13:20:30 -0800
From: Dave Hansen <dave@...1.net>
To: linux-kernel@...r.kernel.org
Cc: x86@...nel.org, Dave Hansen <dave@...1.net>,
dave.hansen@...ux.intel.com
Subject: [RFC][PATCH] x86: nit: wrong page size in init_memory_mapping() printks
From: Dave Hansen <dave.hansen@...ux.intel.com>
With 32-bit non-PAE kernels, we have 2 page sizes available
(at most): 4k and 4M.
Enabling PAE replaces that 4M size with a 2M one (which 64-bit
systems use too).
But, when booting a 32-bit non-PAE kernel, in one of our
early-boot printouts, we say:
[ 0.000000] init_memory_mapping: [mem 0x00000000-0x000fffff]
[ 0.000000] [mem 0x00000000-0x000fffff] page 4k
[ 0.000000] init_memory_mapping: [mem 0x37000000-0x373fffff]
[ 0.000000] [mem 0x37000000-0x373fffff] page 2M
[ 0.000000] init_memory_mapping: [mem 0x00100000-0x36ffffff]
[ 0.000000] [mem 0x00100000-0x003fffff] page 4k
[ 0.000000] [mem 0x00400000-0x36ffffff] page 2M
[ 0.000000] init_memory_mapping: [mem 0x37400000-0x377fdfff]
[ 0.000000] [mem 0x37400000-0x377fdfff] page 4k
Which is obviously wrong. There is no 2M page available. This
is probably because of a badly-named variable: in the map_range
code: PG_LEVEL_2M.
Instead of renaming all the PG_LEVEL_2M's. This patch just
fixes the printout:
[ 0.000000] init_memory_mapping: [mem 0x00000000-0x000fffff]
[ 0.000000] [mem 0x00000000-0x000fffff] page 4k
[ 0.000000] init_memory_mapping: [mem 0x37000000-0x373fffff]
[ 0.000000] [mem 0x37000000-0x373fffff] page 4M
[ 0.000000] init_memory_mapping: [mem 0x00100000-0x36ffffff]
[ 0.000000] [mem 0x00100000-0x003fffff] page 4k
[ 0.000000] [mem 0x00400000-0x36ffffff] page 4M
[ 0.000000] init_memory_mapping: [mem 0x37400000-0x377fdfff]
[ 0.000000] [mem 0x37400000-0x377fdfff] page 4k
[ 0.000000] BRK [0x03206000, 0x03206fff] PGTABLE
Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
---
b/arch/x86/mm/init.c | 28 ++++++++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)
diff -puN arch/x86/mm/init.c~spitting-out-bad-page-size arch/x86/mm/init.c
--- a/arch/x86/mm/init.c~spitting-out-bad-page-size 2015-02-10 11:19:21.839208023 -0800
+++ b/arch/x86/mm/init.c 2015-02-10 11:19:21.848208428 -0800
@@ -238,6 +238,31 @@ static void __init_refok adjust_range_pa
}
}
+static const char *page_size_string(struct map_range *mr)
+{
+ static const char str_1g[] = "1G";
+ static const char str_2m[] = "2M";
+ static const char str_4m[] = "4M";
+ static const char str_4k[] = "4k";
+
+ if (mr->page_size_mask & (1<<PG_LEVEL_1G))
+ return str_1g;
+ /*
+ * 32-bit without PAE has a 4M large page size.
+ * PG_LEVEL_2M is misnamed, but we can at least
+ * print out the right size in the string.
+ */
+ if (IS_ENABLED(CONFIG_X86_32) &&
+ !IS_ENABLED(CONFIG_X86_PAE) &&
+ mr->page_size_mask & (1<<PG_LEVEL_2M))
+ return str_4m;
+
+ if (mr->page_size_mask & (1<<PG_LEVEL_2M))
+ return str_2m;
+
+ return str_4k;
+}
+
static int __meminit split_mem_range(struct map_range *mr, int nr_range,
unsigned long start,
unsigned long end)
@@ -333,8 +358,7 @@ static int __meminit split_mem_range(str
for (i = 0; i < nr_range; i++)
printk(KERN_DEBUG " [mem %#010lx-%#010lx] page %s\n",
mr[i].start, mr[i].end - 1,
- (mr[i].page_size_mask & (1<<PG_LEVEL_1G))?"1G":(
- (mr[i].page_size_mask & (1<<PG_LEVEL_2M))?"2M":"4k"));
+ page_size_string(&mr[i]));
return nr_range;
}
_
--
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