Re: [PATCH 3/4] microblaze: reset: Provide a power off handler through an unaligned PC

Le 04/08/2026 à 13:32, Thomas Weißschuh a écrit :
> microblaze is missing a generic architecture-wide power off mechanism.
> 
> To enable KUnit for microblaze it is necessary for KUnit to shut down
> the machine in a way that QEMU will recognize. The machines emulated by
> QEMU do not provide machine-specific power off functionality which could
> be used.
> However at least the petalogix-s3adsp1800 machine will abort if an
> unaligned instruction is executed. An ugly message will be printed but
> that is not an issue for KUnit.
> 
> Make use of this to provide a power off handler.
> 
> Signed-off-by: Thomas Weißschuh <[email protected]>
> 
> ---
> This is quite hacky. But I didn't find a better solution.

This is hacky. It does work fine here, though, and I also don't have a 
better solution. But I'd feel better about it if a Microblaze person has 
seen it and at least not complained too loudly.

Tested-by: David Gow <[email protected]>

> ---
>   arch/microblaze/Kconfig        |  9 +++++++++
>   arch/microblaze/kernel/reset.c | 21 +++++++++++++++++++++
>   2 files changed, 30 insertions(+)
> 
> diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
> index 484ebb3baedf..0ca8999dd770 100644
> --- a/arch/microblaze/Kconfig
> +++ b/arch/microblaze/Kconfig
> @@ -216,3 +216,12 @@ config MB_MANAGER
>   	  Say N here unless you know what you are doing.
>   
>   endmenu
> +
> +config MB_POWER_OFF_THROUGH_UNALIGNED_PC
> +	bool "Power off through unaligned PC"
> +	help
> +	  This options adds a power off handler which executes an unaligned PC
> +	  so the machine resets in a generic way. This works for the
> +	  petalogix-s3adsp1800 QEMU machine.
> +
> +	  Say N here unless you know what you are doing.
> diff --git a/arch/microblaze/kernel/reset.c b/arch/microblaze/kernel/reset.c
> index 3612a20ca16d..4af660deed3b 100644
> --- a/arch/microblaze/kernel/reset.c
> +++ b/arch/microblaze/kernel/reset.c
> @@ -41,3 +41,24 @@ void machine_restart(char *cmd)
>   	pr_emerg("Reboot failed -- System halted\n");
>   	while (1);
>   }
> +
> +#ifdef CONFIG_MB_POWER_OFF_THROUGH_UNALIGNED_PC
> +static int unaligned_pc_sys_off(struct sys_off_data *data)
> +{
> +	__asm__(
> +		"bri 1\n"
> +	);
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static int __init register_unaligned_pc_sys_off(void)
> +{
> +	struct sys_off_handler *sys_off;
> +
> +	sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, SYS_OFF_PRIO_LOW,
> +					   unaligned_pc_sys_off, NULL);
> +	return PTR_ERR_OR_ZERO(sys_off);
> +}
> +device_initcall(register_unaligned_pc_sys_off);
> +#endif /* CONFIG_MB_POWER_OFF_THROUGH_UNALIGNED_PC */
>