Re: [Xen-devel] [PATCH RESEND v1 1/7] x86: add a flag to enable Intel processor trace

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Jan 16, 2018 at 02:12:27AM +0800, Luwei Kang wrote:
> This patch add a flag to enable Intel PT (Intel processor trace).
> Default value is 1 (enabled).
> 
> Signed-off-by: Luwei Kang <luwei.kang@xxxxxxxxx>
> ---
>  docs/misc/xen-command-line.markdown |  7 +++++++
>  xen/arch/x86/cpu/Makefile           |  1 +
>  xen/arch/x86/cpu/intel_pt.c         | 27 +++++++++++++++++++++++++++
>  xen/include/asm-x86/intel_pt.h      | 26 ++++++++++++++++++++++++++
>  4 files changed, 61 insertions(+)
>  create mode 100644 xen/arch/x86/cpu/intel_pt.c
>  create mode 100644 xen/include/asm-x86/intel_pt.h
> 
> diff --git a/docs/misc/xen-command-line.markdown 
> b/docs/misc/xen-command-line.markdown
> index 781110d..95411cf 100644
> --- a/docs/misc/xen-command-line.markdown
> +++ b/docs/misc/xen-command-line.markdown
> @@ -1009,6 +1009,13 @@ debug hypervisor only).
>  ### idle\_latency\_factor
>  > `= <integer>`
>  
> +### intel\_pt
> +> `= <boolean>`
> +
> +> Default: `true`
> +

After reading the manual a bit I think this option needs to be more
sophisticated. 

The series only implements guest-only tracing, while in the future we might
want host-only tracing and system wide tracing.

Even the other modes aren't implemented yet we should leave room for
them.

Wei.

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