The following commit has been merged into the x86/fred branch of tip: Commit-ID: 7a1d75084df087dcae703d70a49274a3982e3681 Gitweb: https://git.kernel.org/tip/7a1d75084df087dcae703d70a49274a3982e3681 Author: Xin Li <xin3.li@xxxxxxxxx> AuthorDate: Tue, 05 Dec 2023 02:49:57 -08:00 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitterDate: Thu, 25 Jan 2024 19:10:30 +01:00 x86/fred: Disable FRED by default in its early stage To enable FRED, a new kernel command line option "fred" needs to be added. Signed-off-by: Xin Li <xin3.li@xxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Tested-by: Shan Kang <shan.kang@xxxxxxxxx> Link: https://lore.kernel.org/r/20231205105030.8698-9-xin3.li@xxxxxxxxx --- 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 31b3a25..c6c1a2c 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1539,6 +1539,9 @@ 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 0b97bcd..2121ec6 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1484,6 +1484,9 @@ 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
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