[PATCH v10 10/38] x86/fred: Disable FRED by default in its early stage

Xin Li
2023-09-14T05:19:38Z

To enable FRED, a new kernel command line option "fred" needs to be added.

Tested-by: Shan Kang <shan.kang@intel.com>
Signed-off-by: Xin Li <xin3.li@intel.com>
---
Documentation/admin-guide/kernel-parameters.txt | 3 +++
arch/x86/kernel/cpu/common.c | 3 +++
2 files changed, 6 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 0a1731a0f0ef..42def5cc7552 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1525,6 +1525,9 @@
Warning: use of this parameter will taint the kernel
and may cause unknown problems.

+ fred [X86-64]
+ Enable flexible return and event delivery
+
ftrace=[tracer]
[FTRACE] will set and start the specified tracer
as early as possible in order to facilitate early
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 382d4e6b848d..317b4877e9c7 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1486,6 +1486,9 @@ static void __init cpu_parse_early_param(void)
char *argptr = arg, *opt;
int arglen, taint = 0;

+ if (!cmdline_find_option_bool(boot_command_line, "fred"))
+ setup_clear_cpu_cap(X86_FEATURE_FRED);
+
#ifdef CONFIG_X86_32
if (cmdline_find_option_bool(boot_command_line, "no387"))
#ifdef CONFIG_MATH_EMULATION
--
2.34.1