sem

Command Function

This command is used to query information about kernel semaphores.

Syntax

sem [ID_ / fulldata_]

Parameters

Table 1 Parameter description

Parameter

Parameters

Value Range

ID

Specifies the semaphore ID.

[0, 0xFFFFFFFF]

fulldata

Queries information about all the semaphores in use. The information to be printed includes SemID, Count, OriginalCount, Creater(TaskEntry), and LastAccessTime.

N/A

Usage

  • If the parameters are not specified, this command displays the number of used semaphores and the total number of semaphores.

  • If the ID parameter is specified, semaphores of the specified ID are displayed.

  • The fulldata parameter depends on LOSCFG_DEBUG_SEMAPHORE. Before using this parameter, select Enable Semaphore Debugging on menuconfig.

    Debug ---> Enable a Debug Version ---> Enable Debug LiteOS Kernel Resource ---> Enable Semaphore Debugging

Example

Run sem fulldata.

Output

Figure 1 Querying information about all semaphores in use

Table 2 Output

Parameter

Description

SemID

Semaphore ID

Count

Number of used semaphores

NOTE: The ID value can be in decimal or hexadecimal format. When the ID value is within the range of [0, 1023], semaphore information of the specified ID is displayed. If the semaphore ID is not used, a message is displayed to inform you of this case. For other values, a message is displayed indicating that the parameter is incorrect.