On Mon, 22 Apr 2019, Aubrey Li wrote: > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 5ad92419be19..d5a9c5ddd453 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -208,6 +208,7 @@ config X86 > select USER_STACKTRACE_SUPPORT > select VIRT_TO_BUS > select X86_FEATURE_NAMES if PROC_FS > + select PROC_PID_ARCH_STATUS if PROC_FS Can you please stop mixing arch and proc code? There is no point in enabling this on x86 right away. > + > +config PROC_PID_ARCH_STATUS > + bool "Enable /proc/<pid>/arch_status file" Why is this switchable? x86 selects it if PROC_FS is enabled and all other architectures are absolutely not interested in this. > + default n > + help > + Provides a way to examine process architecture specific information. > + See <file:Documentation/filesystems/proc.txt> for more information. Which contains zero information about this file when only this patch is applied. > @@ -94,6 +94,7 @@ > #include <linux/sched/debug.h> > #include <linux/sched/stat.h> > #include <linux/posix-timers.h> > +#include <linux/processor.h> That include is required because it does NOT contain anything useful for this, right? > +/* > + * Add support for task architecture specific output in /proc/pid/arch_status. > + * task_arch_status() must be defined in asm/processor.h > + */ > +#ifdef CONFIG_PROC_PID_ARCH_STATUS > +# ifndef task_arch_status > +# define task_arch_status(m, task) > +# endif What exactly is the point of this macro mess? If an architecture selects CONFIG_PROC_PID_ARCH_STATUS then it has to provide proc_task_arch_status() and the prototype should be in include/linux/proc_fs.h. > +static int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns, > + struct pid *pid, struct task_struct *task) > +{ > + task_arch_status(m, task); > + return 0; > +} > +#endif /* CONFIG_PROC_PID_ARCH_STATUS */ Thanks, tglx