Re: [Minios-devel] [PATCH 25/40] arm64: set the stack for the arm_start_thread

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Shijie,

On 03/11/17 03:12, Huang Shijie wrote:
> When a thread (which is picked by the scheduler) runs at the first time,
> it needs a stack to store the data.
>
> This patch set the stack for the arm_start_thread.
>
> Change-Id: I4cfa18b199cb920e9ebe19bbbe2cf508264b0ba8
> Jira: ENTOS-247
> Signed-off-by: Huang Shijie <shijie.huang@xxxxxxx>
> ---
>   arch/arm/sched.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/arch/arm/sched.c b/arch/arm/sched.c
> index 448fd3e..f691d7d 100644
> --- a/arch/arm/sched.c
> +++ b/arch/arm/sched.c
> @@ -32,6 +32,12 @@ struct thread* arch_create_thread(char *name, void 
> (*function)(void *),
>        * for the initial switch. */
>       thread->sp = (unsigned long) sp - sizeof(unsigned long) * 
> CALLEE_SAVED_REGISTERS;
>   
> +    /*
> +     * Please refer to the stack layout in the comment for 
> __arch_switch_threads.
> +     * We need to set the sp register for arm_start_thread when a thread runs
> +     * at the first time.
> +     */
> +    *(--sp) = thread->sp;
But this is common code between Arm64 and Arm32. How come you don't 
update arm32?
Why do you need to save sp on Arm64 and not Arm32?

>       thread->ip = (unsigned long) arm_start_thread;
>   
>       return thread;
Cheers,

--
Julien Grall

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