lkml.org 
[lkml]   [2022]   [Dec]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH v5 6/6] Documentation: coresight: docs for config load via configfs
On Mon, Dec 19, 2022 at 11:46:38PM +0000, Mike Leach wrote:
> diff --git a/Documentation/trace/coresight/coresight-config.rst b/Documentation/trace/coresight/coresight-config.rst
> index 6d5ffa6f7347..109053eb1b93 100644
> --- a/Documentation/trace/coresight/coresight-config.rst
> +++ b/Documentation/trace/coresight/coresight-config.rst
> @@ -141,11 +141,11 @@ Mount configfs as normal and the 'cs-syscfg' subsystem will appear::
> $ ls /config
> cs-syscfg stp-policy
>
> -This has two sub-directories::
> +This has two sub-directories, with the load and unload attribute files::
>
> $ cd cs-syscfg/
> $ ls
> - configurations features
> + configurations features load unload
>
> The system has the configuration 'autofdo' built in. It may be examined as
> follows::
> @@ -278,9 +278,16 @@ Creating and Loading Custom Configurations
> ==========================================
>
> Custom configurations and / or features can be dynamically loaded into the
> -system by using a loadable module.
> +system by using a loadable module, or by loading a binary configuration
> +file in configfs.
>
> -An example of a custom configuration is found in ./samples/coresight.
> +Loaded configurations can use previously loaded features. The system will
> +ensure that it is not possible to unload a feature that is currently in
> +use, by enforcing the unload order as the strict reverse of the load order.
> +
> +
> +Using a Loadable Module
> +-----------------------
>
> This creates a new configuration that uses the existing built in
> strobing feature, but provides a different set of presets.
> @@ -289,6 +296,187 @@ When the module is loaded, then the configuration appears in the configfs
> file system and is selectable in the same way as the built in configuration
> described above.
>
> -Configurations can use previously loaded features. The system will ensure
> -that it is not possible to unload a feature that is currently in use, by
> -enforcing the unload order as the strict reverse of the load order.
> +The file 'coresight-cfg-sample.c' contains the configuration and module
> +initialisation code needed to create the loadable module.
> +
> +This will be built alongside the kernel modules if select in KConfig.

What config options (CONFIG_) are required for above to work?

> +
> +An example of a custom configuration module is found in './samples/coresight'.
> +
> +Using a Binary Configuration File
> +---------------------------------
> +
> +The './tools/coresight' directory contains example programs to generate and
> +read and print binary configuration files.
> +
> +Building the tools creates the 'coresight-cfg-file-gen' program that will
> +generate a configuration binary 'example1.cscfg' that can be loaded into the
> +system using configfs. The configuration declared in the source file
> +'coresight-cfg-example1.c' is named 'autofdo3' - the name that will be used
> +once loaded.
> +
> +The source files 'coresight-cfg-bufw.h' and 'coresight-cfg-bufw.c' provide a
> +standard function to convert a configuration declared in 'C' into the correct
> +binary buffer format. These files can be re-used to create new custom
> +configurations. Alternatively, addition examples can be added to the

s/addition/additional/

> +'coresight-cfg-file-gen' program::
> +
> + $ ./coresight-cfg-file-gen
> + Coresight Configuration file Generator
> +
> + Generating example1 example
> + Generating example2 example
> +
> +The program 'coresight-cfg-file-read' can read back and print a configuration
> +binary. This is built using the file reader from the driver code
> +(coresight-config-file.c), which is copied over into './tools/coresight' at
> +build time.::
> +
> + ./coresight-cfg-file-read example1.cscfg
> + CoreSight Configuration file reader
> + ============================================
> +
> + Configuration 1
> + Name:- autofdo3
> + Description:-
> + Setup ETMs with strobing for autofdo
> + Supplied presets allow experimentation with mark-space ratio for various loads
> +
> + Uses 1 features:-
> + Feature-1: strobing
> +
> + Provides 4 sets of preset values, 2 presets per set
> + set[0]: 0x7d0, 0x64,
> + set[1]: 0x7d0, 0x3e8,
> + set[2]: 0x7d0, 0x1388,
> + set[3]: 0x7d0, 0x2710,
> +
> + ============================================
> + File contains no features
> +
> +There are additional attributes in the cs-syscfg directory - load and
> +unload that can be used to load and unload configuration binary files. To
> +load, 'cat' the binary config into the load attribute::
> +
> + $ ls /config/cs-syscfg
> + configurations features load unload
> + $ cat example1.cscfg > /config/cs-syscfg/load
> + $ ls /config/cs-syscfg/configurations/
> + autofdo autofdo3
> +
> +To unload, use the same file in the unload attribute::
> +
> + $ cat example1.cscfg > /config/cs-syscfg/unload
> + ls /config/cs-syscfg/configurations/
> + autofdo
> +
> +
> +
> +Binary Configuration File Format
> +--------------------------------
> +
> +The file format is defined in the source file **coresight-config-file.h**

Use single-quote for identifier names for consistency here.

> +
> +The source reader and generator examples produce a binary of this format.
> +
> +This arrangement is reproduced below:-
> +
> +Overall File structure
> +~~~~~~~~~~~~~~~~~~~~~~
> +
> +::
> +
> + [cscfg_file_header] // Mandatory
> + [CONFIG_ELEM]* // Optional - multiple, defined by cscfg_file_header.nr_configs
> + [FEATURE_ELEM]* // Optional - multiple, defined by cscfg_file_header.nr_features
> +
> +File is invalid if both [CONFIG_ELEM] and [FEATURE_ELEM] are omitted.
> +
> +A file that contains only [FEATURE_ELEM] may be loaded, and the features used
> +by subsequently loaded files with [CONFIG_ELEM] elements.
> +
> +Element Name Strings
> +~~~~~~~~~~~~~~~~~~~~
> +
> +Configuration name strings are required to consist of alphanumeric characters and '_' only. Other special characters are not permitted.
> +
> +::
> + my_config_2 // is a valid name.
> + this-bad-config#5 // this will not work
Instead of using code-block for name examples, what about "... For
example, foo_bar is a valid name where as foo-bar# is not."?

> +
> +This is in order to comply with the requirements of the perf command line.
> +
> +It is recommended that Feature and Parameter names use the same convention to allow for future enhancements to the command line syntax.
> +
> +CONFIG_ELEM element
> +~~~~~~~~~~~~~~~~~~~
> +
> +::
> +
> + [cscfg_file_elem_header] // header length value to end of feature strings.
> + [cscfg_file_elem_str] // name of the configuration.
> + // (see element string name requirements)
> + [cscfg_file_elem_str] // description of configuration.
> + [u16 value](nr_presets) // number of defined sets presets values.
> + [u32 value](nr_total_params) // total parameters defined by all used features.
> + [u16 value](nr_feat_refs) // number of features referenced by the configuration
> + [u64 values] * (nr_presets * nr_total_params) // the preset values.
> + [cscfg_file_elem_str] * (nr_feat_refs) // names of features used in the configurations.
> +
> +FEATURE_ELEM element
> +~~~~~~~~~~~~~~~~~~~~
> +
> +::
> +
> + [cscfg_file_elem_header] // header length is total bytes to end of param structures.
> + [cscfg_file_elem_str] // feature name.
> + [cscfg_file_elem_str] // feature description.
> + [u32 value](match_flags) // flags to associate the feature with a device.
> + [u16 value](nr_regs) // number of registers.
> + [u16 value](nr_params) // number of parameters.
> + [cscfg_regval_desc struct] * (nr_regs) // register definitions
> + [PARAM_ELEM] * (nr_params) // parameters definitions
> +
> +PARAM_ELEM element
> +~~~~~~~~~~~~~~~~~~
> +
> +::
> +
> + [cscfg_file_elem_str] // parameter name.
> + [u64 value](param_value) // initial value.
> +
> +Additional definitions.
> +~~~~~~~~~~~~~~~~~~~~~~~

Trim trailing period for section names

> +
> +The following structures are defined in **coresight-config-file.h**
> +
> + * **struct cscfg_file_header** : This structure contains an initial magic number, the total
> + length of the file, and the number of configurations and features in the file.
> + * **struct cscfg_file_elem_header**: This defines the total length and type of a CONFIG_ELEM
> + or a FEATURE_ELEM.
> + * **struct cscfg_file_elem_str**: This defines a string and its length.

Again, for consistency, wrap identifier names in single-quotes.

> +
> +The magic number in cscfg_file_header is defined as two bitfields::
> +
> + [31:8] Fixed magic number to identify file type.
> + [7:0] Current file format version.
> +
> +The following defines determine the maximum overall file size and maximum individual
> +string size::
> +
> + CSCFG_FILE_MAXSIZE // maximum overall file size.
> + CSCFG_FILE_STR_MAXSIZE // maximum individual string size.

For parameter lists in elements, use bullet lists instead.

> +
> +Load Dependencies.
> +~~~~~~~~~~~~~~~~~~

Trim trailing period for section names.
> +
> +Files may be unloaded only in the strict reverse order of loading. This is enforced by the
> +configuration system.
> +
> +This is to ensure that any load dependencies are maintained.
> +
> +A configuration file that contains a CONFIG_ELEM that references named features "feat_A" and "feat_B" will load only if either:-
> +a) "feat_A" and/or "feat_B" has been loaded previously, or are present as built-in / module loaded features.
> +b) "feat_A" and/or "feat_B" are declared as FEAT_ELEM in the same file as the CONFIG_ELEM.

Separate the preceding paragraph and the list with a blank line in order
for the list to be rendered as list.

Thanks.

--
An old man doll... just what I always wanted! - Clara
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2023-03-26 23:16    [W:0.105 / U:0.560 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site