[DTrace-devel] [PATCH v2 20/20] doc: Add rawfbt provider documentation

[Kris Van Hees]

Small grammar nit below ..

On Tue, Oct 21, 2025, 23:23 <eugene.loh at oracle.com> wrote:

> From: Eugene Loh <eugene.loh at oracle.com>
>
> Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
> ---
>  doc/userguide/index.md                        |  4 ++
>  doc/userguide/reference/dtrace_providers.md   |  2 +
>  .../reference/dtrace_providers_rawfbt.md      | 50 +++++++++++++++++++
>  3 files changed, 56 insertions(+)
>  create mode 100644 doc/userguide/reference/dtrace_providers_rawfbt.md
>
> diff --git a/doc/userguide/index.md b/doc/userguide/index.md
> index f86c8b9e5..da9a08687 100644
> --- a/doc/userguide/index.md
> +++ b/doc/userguide/index.md
> @@ -241,6 +241,10 @@
>          -   [profile Probe
> Arguments](reference/dtrace_providers_profile.md#dt_ref_profargs_prov)
>          -   [profile Probe
> Creation](reference/dtrace_providers_profile.md#dt_ref_profprobecreate_prov)
>          -   [profile
> Stability](reference/dtrace_providers_profile.md#dt_ref_profstab_prov)
> +    -   [Raw FBT Provider](reference/dtrace_providers_rawfbt.md)
> +        -   [rawfbt
> Probes](reference/dtrace_providers_rawfbt.md#dt_ref_rawfbtprobes_prov)
> +        -   [rawfbt Probe
> Arguments](reference/dtrace_providers_rawfbt.md#dt_ref_rawfbtargs_prov)
> +        -   [rawfbt
> Stability](reference/dtrace_providers_rawfbt.md#dt_ref_rawfbtstab_prov)
>      -   [Rawtp
> Provider](reference/dtrace_providers_rawtp.md#dt_ref_rawtp_prov)
>          -   [rawtp
> Stability](reference/dtrace_providers_rawtp.md#dt_ref_rawtpstab_prov)
>      -   [Sched
> Provider](reference/dtrace_providers_sched.md#dt_ref_sched_prov)
> diff --git a/doc/userguide/reference/dtrace_providers.md
> b/doc/userguide/reference/dtrace_providers.md
> index f11bacb2f..741a34fc8 100644
> --- a/doc/userguide/reference/dtrace_providers.md
> +++ b/doc/userguide/reference/dtrace_providers.md
> @@ -21,6 +21,8 @@ The `pid` provider traces a user process, both function
> `entry` and `return`, an
>  The `proc` provider makes available the probes that pertain to the
> following activities: process creation and termination, LWP creation and
> termination, execution of new program images, and signal sending and
> handling.
>  -   **[Profile Provider](../reference/dtrace_providers_profile.md)**
>  The `profile` provider includes probes that are associated with an
> interrupt that fires at some regular, specified time interval.
> +-   **[Raw FBT Provider](../reference/dtrace_providers_rawfbt.md)**
> +The `rawfbt` provider is a version of the `fbt` provider based on kprobes
> and allowing probing of synthetic function variants generated by the
> compiler.
>

Either "and allows" or "allowing".

 -   **[Rawtp Provider](../reference/dtrace_providers_rawtp.md)**
>  The `rawtp` provider gives DTrace users access to the raw tracepoints
> exposed by the kernel tracing system, including access to the untranslated
> arguments of the associated tracepoint events.
>  -   **[Sched Provider](../reference/dtrace_providers_sched.md)**
> diff --git a/doc/userguide/reference/dtrace_providers_rawfbt.md
> b/doc/userguide/reference/dtrace_providers_rawfbt.md
> new file mode 100644
> index 000000000..7b1fc7723
> --- /dev/null
> +++ b/doc/userguide/reference/dtrace_providers_rawfbt.md
> @@ -0,0 +1,50 @@
> +# Raw FBT Provider
> +
> +The [fbt provider](../reference/dtrace_providers_fbt.md) consists of
> +probes that are associated with the entry to and return from most
> functions
> +in the Linux kernel.  It does not support tracing synthetic functions,
> +that is, compiler-generated functions with a . in their name.
> +
> +In contrast, the `rawfbt` provider implements a variant of the FBT
> provider
> +and always uses kprobes.  It does allow tracing of synthetic functions,
> such
> +as compiler-generated optimized variants of functions with . suffixes.
> +
> +You can see the raw FBT probes on your system with:
> +
> +```
> +sudo dtrace -lP rawfbt
> +```
> +
> +As with the `fbt` provider, there could be tens of thousands of probes,
> +and effective use requires knowledge of the kernel implementation.
> +
> +**Parent topic:**[DTrace Provider
> Reference](../reference/dtrace_providers.md)
> +
> +## rawfbt Probes <a id="dt_ref_rawfbtprobes_prov">
> +
> +The module name of a `rawfbt` probe is `vmlinux` for built-in modules.
> +The function name is the probed function.
> +The probe name is either `entry` or `return`.
> +
> +## rawfbt Probe Arguments <a id="dt_ref_rawfbtargs_prov">
> +
> +The arguments to `entry` probes are the same as the arguments to the
> corresponding operating system kernel function.
> +These arguments can be accessed as `int64_t` values by using the `arg0`,
> `arg1`, `arg2`, ... variables.
> +
> +If the function has a return value, the return value is stored in `arg1`
> of the `return` probe.
> +If a function doesn't have a return value, `arg1` isn't defined.
> +
> +There are no typed `args[]` arguments for any `rawfbt` probes.
> +
> +## rawfbt Stability <a id="dt_ref_rawfbtstab_prov">
> +
> +The `rawfbt` provider uses DTrace's stability mechanism to describe its
> stabilities.
> +These stability values are listed in the following table.
> +
> +| Element   | Name Stability | Data Stability | Dependency Class |
> +| :---      | :---           | :---           | :---             |
> +| Provider  | Evolving       | Evolving       | Common           |
> +| Module    | Private        | Private        | Unknown          |
> +| Function  | Private        | Private        | ISA              |
> +| Name      | Evolving       | Evolving       | Common           |
> +| Arguments | Private        | Private        | ISA              |
> --
> 2.47.3
>
>
>
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