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platform: fix FreeRTOS scheduler on Zynq-A9 QEMU #69

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Merged
zevorn merged 1 commit into from
Mar 18, 2026
Merged

platform: fix FreeRTOS scheduler on Zynq-A9 QEMU #69

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2 changes: 1 addition & 1 deletion platform/zynq-a9/FreeRTOSConfig.h
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@
#define configUSE_TICKLESS_IDLE 0
#define configCPU_CLOCK_HZ 100000000UL
#define configTICK_RATE_HZ 1000
#define configMAX_PRIORITIES 8
#define configMAX_PRIORITIES 32
#define configMINIMAL_STACK_SIZE 256
#define configMAX_TASK_NAME_LEN 16
#define configIDLE_SHOULD_YIELD 1
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2 changes: 1 addition & 1 deletion platform/zynq-a9/FreeRTOS_asm_vectors.S
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Original file line number Diff line number Diff line change
Expand Up @@ -78,7 +78,7 @@
.extern FreeRTOS_IRQ_Handler
.extern FreeRTOS_SWI_Handler

.section .freertos_vectors
.section .freertos_vectors, "ax"
_freertos_vector_table:
B _boot
B FreeRTOS_Undefined
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5 changes: 3 additions & 2 deletions platform/zynq-a9/link.ld
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Expand Up @@ -33,13 +33,14 @@ SECTIONS
*(.boot)
} > DDR

.freertos_vectors : {
/* 32-byte aligned for ARM VBAR requirement */
.freertos_vectors : ALIGN(32) {
KEEP(*(.freertos_vectors))
KEEP(*(.vectors))
} > DDR

/* Executable code */
.text : {
.text : ALIGN(4) {
*(.text)
*(.text.*)
*(.gnu.linkonce.t.*)
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14 changes: 11 additions & 3 deletions platform/zynq-a9/startup.S
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,14 @@ _reset:
/* Disable interrupts */
cpsid if

/* Enable VFP/NEON (CP10 + CP11 full access) */
mrc p15, 0, r0, c1, c0, 2
orr r0, r0, #(0xF << 20)
mcr p15, 0, r0, c1, c0, 2
isb
mov r0, #(1 << 30) /* FPEXC.EN */
vmsr fpexc, r0

/* Set VBAR to FreeRTOS vector table */
ldr r0, =_freertos_vector_table
mcr p15, 0, r0, c12, c0, 0
Expand All @@ -64,9 +72,9 @@ _reset:
cps #0x1b
ldr sp, =__undef_stack

/* Switch to System mode (shared with User) */
cps #0x1f
ldr sp, =__stack
/* Switch to Supervisor mode — FreeRTOS ARM_CA9 port
* expects to start the scheduler from SVC mode. */
cps #0x13

/* Clear BSS */
ldr r0, =__bss_start
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