Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 0790c9aa authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
Browse files

x86/mm: Add the 'nopcid' boot option to turn off PCID 



The parameter is only present on x86_64 systems to save a few bytes,
as PCID is always disabled on x86_32.

Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Reviewed-by: default avatarNadav Amit <nadav.amit@gmail.com>
Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/8bbb2e65bcd249a5f18bfb8128b4689f08ac2b60.1498751203.git.luto@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent cba4671a

Documentation/admin-guide/kernel-parameters.txt

+2 −0
Original line number Diff line number Diff line
@@ -2657,6 +2657,8 @@ 
	nopat		[X86] Disable PAT (page attribute table extension of

			pagetables) support.



	nopcid		[X86-64] Disable the PCID cpu feature.



	norandmaps	Don't use address space randomization.  Equivalent to

			echo 0 > /proc/sys/kernel/randomize_va_space

arch/x86/kernel/cpu/common.c

+18 −0
Original line number Diff line number Diff line
@@ -168,6 +168,24 @@ static int __init x86_mpx_setup(char *s) 
}

__setup("nompx", x86_mpx_setup);



#ifdef CONFIG_X86_64

static int __init x86_pcid_setup(char *s)

{

	/* require an exact match without trailing characters */

	if (strlen(s))

		return 0;



	/* do not emit a message if the feature is not present */

	if (!boot_cpu_has(X86_FEATURE_PCID))

		return 1;



	setup_clear_cpu_cap(X86_FEATURE_PCID);

	pr_info("nopcid: PCID feature disabled\n");

	return 1;

}

__setup("nopcid", x86_pcid_setup);

#endif



static int __init x86_noinvpcid_setup(char *s)

{

	/* noinvpcid doesn't accept parameters */