On Wed, Oct 09, 2024 at 12:10:50AM +0800, Pengyu Zhang wrote: > 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@xxxxxxxxx> Reviewed-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx> > --- > 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 > -- > 2.25.1 > -- Sincerely yours, Mike.
