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Reduce SVCall priority on ARMv7-M with MPU #1470

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Reduce SVCall priority on ARMv7-M with MPU #1470

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4752ca3
Reduce SVCall priority on ARMv7/8-M with MPU
jefftenney Aug 18, 2026
3044505
Revert ARMv8-M changes
jefftenney Aug 19, 2026
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11 changes: 6 additions & 5 deletions portable/GCC/ARM_CM3_MPU/port.c
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Original file line number Diff line number Diff line change
Expand Up @@ -96,12 +96,14 @@ typedef void ( * portISR_t )( void );
#define portPERIPHERALS_START_ADDRESS 0x40000000UL
#define portPERIPHERALS_END_ADDRESS 0x5FFFFFFFUL

/* Constants required to access and manipulate the SysTick. */
/* Constants required to access and manipulate the SysTick and other FreeRTOS
* interrupts. */
#define portNVIC_SYSTICK_INT ( 0x00000002UL )
#define portNVIC_SYSTICK_ENABLE ( 0x00000001UL )
#define portMIN_INTERRUPT_PRIORITY ( 255UL )
#define portNVIC_PENDSV_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 16UL )
#define portNVIC_SYSTICK_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 24UL )
#define portNVIC_SVC_PRI ( ( ( uint32_t ) configMAX_SYSCALL_INTERRUPT_PRIORITY - 1UL ) << 24UL )

/* Constants required to set up the initial stack. */
#define portINITIAL_XPSR ( 0x01000000 )
Expand Down Expand Up @@ -877,12 +879,11 @@ BaseType_t xPortStartScheduler( void )
}
#endif /* configASSERT_DEFINED */

/* Make PendSV and SysTick the lowest priority interrupts, and make SVCall
* the highest priority. */
/* Make PendSV and SysTick the lowest priority interrupts, and configure
* SVCall for sufficient preemption priority. */
portNVIC_SHPR3_REG |= portNVIC_PENDSV_PRI;
portNVIC_SHPR3_REG |= portNVIC_SYSTICK_PRI;
portNVIC_SHPR2_REG = 0;

portNVIC_SHPR2_REG = portNVIC_SVC_PRI;

/* Configure the regions in the MPU that are common to all tasks. */
prvSetupMPU();
Expand Down
10 changes: 6 additions & 4 deletions portable/GCC/ARM_CM4_MPU/port.c
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Original file line number Diff line number Diff line change
Expand Up @@ -106,12 +106,14 @@ typedef void ( * portISR_t )( void );
#define portPERIPHERALS_START_ADDRESS 0x40000000UL
#define portPERIPHERALS_END_ADDRESS 0x5FFFFFFFUL

/* Constants required to access and manipulate the SysTick. */
/* Constants required to access and manipulate the SysTick and other FreeRTOS
* interrupts. */
#define portNVIC_SYSTICK_INT ( 0x00000002UL )
#define portNVIC_SYSTICK_ENABLE ( 0x00000001UL )
#define portMIN_INTERRUPT_PRIORITY ( 255UL )
#define portNVIC_PENDSV_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 16UL )
#define portNVIC_SYSTICK_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 24UL )
#define portNVIC_SVC_PRI ( ( ( uint32_t ) configMAX_SYSCALL_INTERRUPT_PRIORITY - 1UL ) << 24UL )

/* Constants required to manipulate the VFP. */
#define portFPCCR ( ( volatile uint32_t * ) 0xe000ef34UL ) /* Floating point context control register. */
Expand Down Expand Up @@ -965,11 +967,11 @@ BaseType_t xPortStartScheduler( void )
}
#endif /* configASSERT_DEFINED */

/* Make PendSV and SysTick the lowest priority interrupts, and make SVCall
* the highest priority. */
/* Make PendSV and SysTick the lowest priority interrupts, and configure
* SVCall for sufficient preemption priority. */
portNVIC_SHPR3_REG |= portNVIC_PENDSV_PRI;
portNVIC_SHPR3_REG |= portNVIC_SYSTICK_PRI;
portNVIC_SHPR2_REG = 0;
portNVIC_SHPR2_REG = portNVIC_SVC_PRI;

/* Configure the regions in the MPU that are common to all tasks. */
prvSetupMPU();
Expand Down
8 changes: 5 additions & 3 deletions portable/IAR/ARM_CM4F_MPU/port.c
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Original file line number Diff line number Diff line change
Expand Up @@ -120,9 +120,11 @@ typedef void ( * portISR_t )( void );
#define portCORTEX_M7_r0p1_ID ( 0x410FC271UL )
#define portCORTEX_M7_r0p0_ID ( 0x410FC270UL )

/* Constants to manipulate FreeRTOS interrupt priorities. */
#define portMIN_INTERRUPT_PRIORITY ( 255UL )
#define portNVIC_PENDSV_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 16UL )
#define portNVIC_SYSTICK_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 24UL )
#define portNVIC_SVC_PRI ( ( ( uint32_t ) configMAX_SYSCALL_INTERRUPT_PRIORITY - 1UL ) << 24UL )

/* Constants used to check the installation of the FreeRTOS interrupt handlers. */
#define portSCB_VTOR_REG ( *( ( portISR_t ** ) 0xE000ED08 ) )
Expand Down Expand Up @@ -862,11 +864,11 @@ BaseType_t xPortStartScheduler( void )
}
#endif /* configASSERT_DEFINED */

/* Make PendSV and SysTick the lowest priority interrupts, and make SVCall
* the highest priority. */
/* Make PendSV and SysTick the lowest priority interrupts, and configure
* SVCall for sufficient preemption priority. */
portNVIC_SHPR3_REG |= portNVIC_PENDSV_PRI;
portNVIC_SHPR3_REG |= portNVIC_SYSTICK_PRI;
portNVIC_SHPR2_REG = 0;
portNVIC_SHPR2_REG = portNVIC_SVC_PRI;

/* Configure the regions in the MPU that are common to all tasks. */
prvSetupMPU();
Expand Down
11 changes: 6 additions & 5 deletions portable/RVDS/ARM_CM4_MPU/port.c
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Original file line number Diff line number Diff line change
Expand Up @@ -95,13 +95,15 @@ typedef void ( * portISR_t )( void );
#define portPERIPHERALS_START_ADDRESS 0x40000000UL
#define portPERIPHERALS_END_ADDRESS 0x5FFFFFFFUL

/* Constants required to access and manipulate the SysTick. */
/* Constants required to access and manipulate the SysTick and other FreeRTOS
* interrupts. */
#define portNVIC_SYSTICK_CLK ( 0x00000004UL )
#define portNVIC_SYSTICK_INT ( 0x00000002UL )
#define portNVIC_SYSTICK_ENABLE ( 0x00000001UL )
#define portMIN_INTERRUPT_PRIORITY ( 255UL )
#define portNVIC_PENDSV_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 16UL )
#define portNVIC_SYSTICK_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 24UL )
#define portNVIC_SVC_PRI ( ( ( uint32_t ) configMAX_SYSCALL_INTERRUPT_PRIORITY - 1UL ) << 24UL )

/* Constants required to manipulate the VFP. */
#define portFPCCR ( ( volatile uint32_t * ) 0xe000ef34UL ) /* Floating point context control register. */
Expand Down Expand Up @@ -966,12 +968,11 @@ BaseType_t xPortStartScheduler( void )
}
#endif /* configASSERT_DEFINED */

/* Make PendSV and SysTick the same priority as the kernel, and the SVC
* handler highest priority so it can be used to exit a critical section
* (where lower priorities are masked). */
/* Make PendSV and SysTick the lowest priority interrupts, and configure
* SVCall for sufficient preemption priority. */
portNVIC_SHPR3_REG |= portNVIC_PENDSV_PRI;
portNVIC_SHPR3_REG |= portNVIC_SYSTICK_PRI;
portNVIC_SHPR2_REG = 0;
portNVIC_SHPR2_REG = portNVIC_SVC_PRI;

/* Configure the regions in the MPU that are common to all tasks. */
prvSetupMPU();
Expand Down
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