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arm64: fix fvp smp faild to boot #14476

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merged 1 commit into from
Oct 24, 2024
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arm64: fix fvp smp faild to boot #14476

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2 changes: 1 addition & 1 deletion arch/arm64/src/common/arm64_cpustart.c
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Original file line number Diff line number Diff line change
Expand Up @@ -210,7 +210,7 @@ int up_cpu_start(int cpu)
#ifdef CONFIG_ARM64_SMP_BUSY_WAIT
uint32_t *address = (uint32_t *)CONFIG_ARM64_SMP_BUSY_WAIT_FLAG_ADDR;
*address = 1;
up_flush_dcache((uintptr_t)address, sizeof(address));
up_flush_dcache((uintptr_t)address, (uintptr_t)address + sizeof(address));
#endif

arm64_start_cpu(cpu);
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2 changes: 2 additions & 0 deletions boards/arm64/fvp-v8r/fvp-armv8r/configs/nsh_smp/defconfig
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Expand Up @@ -14,6 +14,8 @@ CONFIG_ARCH_CHIP_FVP_ARMV8R=y
CONFIG_ARCH_CHIP_FVP_R82=y
CONFIG_ARCH_EARLY_PRINT=y
CONFIG_ARCH_INTERRUPTSTACK=4096
CONFIG_ARM64_SMP_BUSY_WAIT=y
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Any idea why FVP needs busy wait?

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The FVP SMP startup has always been using the busywait strategy. Before my modification, it serially waited for a fixed global variable (cpu_ready_flag). After I changed it to parallel startup for CPUs (1 to n), I added a wait address for more generality. However, at that time, the FVP SMP was not configured accordingly, leading to this error.

Additionally, let me mention that the arm64 QEMU SMP startup uses the PSCI method, rather than busywait.

CONFIG_ARM64_SMP_BUSY_WAIT_FLAG_ADDR=0x60000
CONFIG_ARM64_STRING_FUNCTION=y
CONFIG_BUILTIN=y
CONFIG_DEBUG_ASSERTIONS=y
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6 changes: 6 additions & 0 deletions boards/arm64/fvp-v8r/fvp-armv8r/scripts/dramboot.ld
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Expand Up @@ -18,6 +18,8 @@
*
****************************************************************************/

#include <nuttx/config.h>

OUTPUT_ARCH(aarch64)

ENTRY(__start)
Expand Down Expand Up @@ -93,6 +95,10 @@ SECTIONS
} :text
_edata = .; /* End+1 of .data */

#if defined(CONFIG_SMP) && defined(CONFIG_ARM64_SMP_BUSY_WAIT)
. = CONFIG_ARM64_SMP_BUSY_WAIT_FLAG_ADDR + 4;
#endif

.bss : { /* BSS */
. = ALIGN(8);
_sbss = .;
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