Re: [RFC patch] use thread.on_ustack to determine if on user stack

Fenghua Yu
2007-10-15T23:26:52Z

On Mon, Oct 15, 2007 at 12:28:05PM +0800, Luming Yu wrote:
> So my problem is I don't know if it is true that pUStk =
> thread.on_ustack in fsys mode. And I didn't locate the code that the
> thread.on_ustack is cleared to 0 during fsys mode.
> So please help.

In fsys call, pUStk is never equal to thread.on_ustack. Here is the code in
fsys_bubble_down() in fsys.S.

....
st1 [r16]=r0 // M2|3 clear current->thread.on_ustack flag
....
cmp.ne pKStk,pUStk=r0,r0 // A set pKStk <- 0, pUStk <- 1
....

The code shows that thread.on_ustack=0 and pUStk=1 during fsys setup phase. The
two should be equal in other cases than fsys. Seems the two similar names cause
confusion.

Thanks.

-Fenghua