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Merged
merged 2 commits into from
Dec 12, 2018
Merged

Document how to turn MPU off at compile time #868

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5645f24
Add information on how to disable the MPU
c1728p9 Dec 10, 2018
c2947e9
Update platform configs for MPU
c1728p9 Dec 10, 2018
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2 changes: 2 additions & 0 deletions docs/api/platform/MpuManagement.md
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Expand Up @@ -13,6 +13,8 @@ Mbed OS handles MPU management automatically in the following situations:

<span class="notes">**Note:** Memory protection should be transparent to most applications and libraries because Mbed OS handles it automatically for operations that need to disable MPU protections, such as flash programming. This is an advanced feature intended for use by advanced developers; it is not required.</span>

<span class="notes">**Note:** The configuration value `platform.use-mpu` can be set to `false` to remove the MPU driver and save code space.</span>

#### RAM execute lock

After boot, execution from RAM is not allowed. Libraries requiring the ability to execute from RAM can enable this by acquiring the RAM execution lock. The RAM execution lock has a count associated with it, and you can lock it multiple times. Execution from RAM is disabled only when all components have unlocked it.
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29 changes: 28 additions & 1 deletion docs/reference/configuration/Platform.md
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Expand Up @@ -8,10 +8,23 @@ The following is the complete list of platform configuration parameters, as gene
Configuration parameters
------------------------

Name: platform.all-stats-enabled
Description: Set to 1 to enable all platform stats. When enabled the functions mbed_stats_*_get returns non-zero data. See mbed_stats.h for more information
Defined by: library:platform
No value set
Name: platform.cpu-stats-enabled
Description: Set to 1 to enable cpu stats. When enabled the function mbed_stats_cpu_get returns non-zero data. See mbed_stats.h for more information
Defined by: library:platform
No value set
Name: platform.crash-capture-enabled
Description: Enables crash context capture when the system enters a fatal error/crash.
Defined by: library:platform
No value set
Name: platform.cthunk_count_max
Description: The maximum CThunk objects used at the same time. This must be greater than 0 and less 256
Defined by: library:platform
Macro name: MBED_CONF_PLATFORM_CTHUNK_COUNT_MAX
Value: 8 (set by library:platform)
Name: platform.default-serial-baud-rate
Description: Default baud rate for a Serial or RawSerial instance (if not specified in the constructor)
Defined by: library:platform
Expand All @@ -25,7 +38,7 @@ Name: platform.error-decode-http-url-str
Description: HTTP URL string for ARM Mbed-OS Error Decode microsite
Defined by: library:platform
Macro name: MBED_CONF_PLATFORM_ERROR_DECODE_HTTP_URL_STR
Value: "\nFor more info, visit: https:/\/armmbed.github.io/mbedos-error/?error=0x%08X" (set by library:platform)
Value: "\nFor more info, visit: https://armmbed.github.io/mbedos-error/?error=0x%08X" (set by library:platform)
Name: platform.error-filename-capture-enabled
Description: Enables capture of filename and line number as part of error context capture, this works only for debug and develop builds. On release builds, filename capture is always disabled
Defined by: library:platform
Expand All @@ -39,6 +52,15 @@ Name: platform.error-hist-size
Defined by: library:platform
Macro name: MBED_CONF_PLATFORM_ERROR_HIST_SIZE
Value: 4 (set by library:platform)
Name: platform.error-reboot-max
Description: Maximum number of auto reboots permitted when an error happens.
Defined by: library:platform
Macro name: MBED_CONF_PLATFORM_ERROR_REBOOT_MAX
Value: 1 (set by library:platform)
Name: platform.fatal-error-auto-reboot-enabled
Description: Setting this to true enables auto-reboot on a fatal error.
Defined by: library:platform
No value set
Name: platform.force-non-copyable-error
Description: Force compile time error when a NonCopyable object is copied
Defined by: library:platform
Expand Down Expand Up @@ -94,4 +116,9 @@ Name: platform.thread-stats-enabled
Description: Set to 1 to enable thread stats. When enabled the function mbed_stats_thread_get_each returns non-zero data. See mbed_stats.h for more information
Defined by: library:platform
No value set
Name: platform.use-mpu
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This is still a bit too cryptic (or the Mbed OS config system is). So, how do I REALLY disable it? I think I need to modify the mbed_app.json, but how? (Noobie question, playing the devils advocate here).

Description: Use the MPU if available to fault execution from RAM and writes to ROM. Can be disabled to reduce image size.
Defined by: library:platform
Macro name: MBED_CONF_PLATFORM_USE_MPU
Value: 1 (set by library:platform)
```