From 6a32c8dfec8126040a3f5484f4f7301ca96d697c Mon Sep 17 00:00:00 2001 From: Pengyu Zhang Date: Wed, 9 Oct 2024 22:41:35 +0800 Subject: Docs/mm: Fix a mistake for pfn in page_tables.rst 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 Reviewed-by: Linus Walleij Reviewed-by: Zenghui Yu Reviewed-by: Mike Rapoport (Microsoft) Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20241009144135.12453-1-zpenya1314@gmail.com --- Documentation/mm/page_tables.rst | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Documentation/mm/page_tables.rst b/Documentation/mm/page_tables.rst index be47b192a596..e7c69cc32493 100644 --- a/Documentation/mm/page_tables.rst +++ b/Documentation/mm/page_tables.rst @@ -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 -- cgit v1.2.3