Documentation: x86: Contiguous cbm isn’t all X86 [Linux 5.3]

This Linux kernel change "Documentation: x86: Contiguous cbm isn’t all X86" is included in the Linux 5.3 release. This change is authored by James Morse <james.morse [at]> on Fri Jun 7 16:14:06 2019 +0100. The commit for this change in Linux stable tree is eb8ed28 (patch).

Documentation: x86: Contiguous cbm isn't all X86

Since commit 4d05bf71f157 ("x86/resctrl: Introduce AMD QOS feature")
resctrl has supported non-contiguous cache bit masks. The interface
for this is currently try-it-and-see.

Update the documentation to say Intel CPUs have this requirement,
instead of X86.

Cc: Babu Moger <>
Signed-off-by: James Morse <>
Signed-off-by: Jonathan Corbet <>

There are 2 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 Documentation/x86/resctrl_ui.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/x86/resctrl_ui.rst b/Documentation/x86/resctrl_ui.rst
index 225cfd4..066f94e 100644
--- a/Documentation/x86/resctrl_ui.rst
+++ b/Documentation/x86/resctrl_ui.rst
@@ -342,7 +342,7 @@ For cache resources we describe the portion of the cache that is available
 for allocation using a bitmask. The maximum value of the mask is defined
 by each cpu model (and may be different for different cache levels). It
 is found using CPUID, but is also provided in the "info" directory of
-the resctrl file system in "info/{resource}/cbm_mask". X86 hardware
+the resctrl file system in "info/{resource}/cbm_mask". Intel hardware
 requires that these masks have all the '1' bits in a contiguous block. So
 0x3, 0x6 and 0xC are legal 4-bit masks with two bits set, but 0x5, 0x9
 and 0xA are not.  On a system with a 20-bit mask each bit represents 5%

Leave a Reply

Your email address will not be published. Required fields are marked *