Thread (3 messages) 3 messages, 2 authors, 2017-06-01

Re: [PATCH v2] powerpc/64s: Add dt_cpu_ftrs boot time setup option

From: Nicholas Piggin <npiggin@gmail.com>
Date: 2017-05-30 07:23:21

On Tue, 30 May 2017 16:28:09 +1000
Michael Ellerman [off-list ref] wrote:
From: Nicholas Piggin <npiggin@gmail.com>

Provide a dt_cpu_ftrs= cmdline option to disable the dt_cpu_ftrs CPU
feature discovery, and fall back to the "cputable" based version.

Also allow control of advertising unknown features to userspace and
with this parameter, and remove the clunky CONFIG option.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Add explicit early check of bootargs in dt_cpu_ftrs_init()]
Thanks for fixing that up. The patch is more yours than mine now :P
quoted hunk ↗ jump to hunk
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -866,6 +866,16 @@
 
 	dscc4.setup=	[NET]
 
+	dt_cpu_ftrs=	[PPC]
+			Format: {"off" | "known"}
+			Control how the dt_cpu_ftrs device-tree binding is
+			used for CPU feature discovery and setup (if it
+			exists).
+			off: Do not use it, fall back to legacy cpu table.
+			known: Do not pass through unknown features to guests
+			or userspace, only those that the kernel is not aware
+			of.
Well that's not the right number of nots. Better make it:

+			known: Do not pass through unknown features to guests
+			or userspace, only those that the kernel is not not
+			aware of.
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