Re: [Alpha/Linux ] Stack layout/and register values for ret_from_sys_call

[Richard Henderson]

On Mon, Dec 17, 2001 at 11:50:57PM +0530, Aneesh Kumar K.V wrote:
>  Can someone explain me what should be the stack layout and register
> value( if there is any restriction ) before calling ret_from_syscall for
> Alpha.

Top of stack should contain a struct pt_regs.  See asm/ptrace.h.

>   lda     $8,0x3fff
>   bic     $30,$8,$8
> 
> If someone can expain what happens in the above two assembly statement
> it will be really helpful.

This computes the value for "current".  The stack plus task structure
is aligned on a two-page boundary.  See task_union in linux/sched.h.

r~