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Docs/mm: Fix a mistake for pfn in page_tables.rst

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The documentation incorrectly calculate the pfn value as 0x3fffff,
which should be 0x3ffff instead. It is obtained by right-shifting
0xffffc000 by 14 bits.

This patch corrects the value to prevent any potential confusion
for developers referencing this document.

Signed-off-by: Pengyu Zhang <zpenya1314@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Zenghui Yu <zenghui.yu@linux.dev>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20241009144135.12453-1-zpenya1314@gmail.com
This commit is contained in:
Pengyu Zhang 2024-10-09 22:41:35 +08:00 committed by Jonathan Corbet
parent 443165227d
commit 6a32c8dfec
1 changed files with 1 additions and 1 deletions
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2
Documentation/mm/page_tables.rst
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@ -29,7 +29,7 @@ address.
With a page granularity of 4KB and a address range of 32 bits, pfn 0 is at
address 0x00000000, pfn 1 is at address 0x00001000, pfn 2 is at 0x00002000
and so on until we reach pfn 0xfffff at 0xfffff000. With 16KB pages pfs are
at 0x00004000, 0x00008000 ... 0xffffc000 and pfn goes from 0 to 0x3fffff.
at 0x00004000, 0x00008000 ... 0xffffc000 and pfn goes from 0 to 0x3ffff.
As you can see, with 4KB pages the page base address uses bits 12-31 of the
address, and this is why `PAGE_SHIFT` in this case is defined as 12 and