help about trap_setup..

help about trap_setup..

[Bob]

In trap path "trap_setup", if in trap window we will jmp to "trap_setup_kernel_spill". 
 
  /* See if we are in the trap window. */
  93        andcc   %t_twinmask, %t_wim, %g0
  94        bne     trap_setup_kernel_spill         ! in trap window, clean up
  95         nop
  96
  97        /* Trap from kernel with a window available.
  98         * Just do it...
  99         */
 100        jmpl    %t_retpc + 0x8, %g0     ! return to caller
 101         mov    %t_kstack, %sp          ! jump onto new stack
 102
 103trap_setup_kernel_spill:
 104        ld      [%curptr + TI_UWINMASK], %g1
 105        orcc    %g0, %g1, %g0
 106        bne     trap_setup_user_spill   ! there are some user windows, yuck

But where is the %curptr in line 104 is setted? 
 
the comment said   #define curptr g6 /* Set after pt_regs frame is built */ 
 
but i can't find the code set %g6 in these scene. 
 
what'more, what are "user windows" like the line 106 said meaning. There need a lot of particular dealing, 
 
I am still reading it. 
 
Thanks! 

---
Best regards

Bob Liu
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RE: help about trap_setup..

[Bob]

Still no answer...



> From: bo-liu@hotmail.com
> To: sparclinux@vger.kernel.org
> Subject: help about trap_setup..
> Date: Thu, 11 Dec 2008 11:17:54 +0800
> 
> 
> In trap path "trap_setup", if in trap window we will jmp to "trap_setup_kernel_spill". 
> 
> /* See if we are in the trap window. */
> 93 andcc %t_twinmask, %t_wim, %g0
> 94 bne trap_setup_kernel_spill ! in trap window, clean up
> 95 nop
> 96
> 97 /* Trap from kernel with a window available.
> 98 * Just do it...
> 99 */
> 100 jmpl %t_retpc + 0x8, %g0 ! return to caller
> 101 mov %t_kstack, %sp ! jump onto new stack
> 102
> 103trap_setup_kernel_spill:
> 104 ld [%curptr + TI_UWINMASK], %g1
> 105 orcc %g0, %g1, %g0
> 106 bne trap_setup_user_spill ! there are some user windows, yuck
> 
> But where is the %curptr in line 104 is setted? 
> 
> the comment said #define curptr g6 /* Set after pt_regs frame is built */ 
> 
> but i can't find the code set %g6 in these scene. 
> 
> what'more, what are "user windows" like the line 106 said meaning. There need a lot of particular dealing, 
> 
> I am still reading it. 
> 
> Thanks! 
> 
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Re: help about trap_setup..

[Sam Ravnborg]

On Fri, Dec 12, 2008 at 05:02:36PM +0800, Bob wrote:
> 
> Still no answer...

From the outside it looks like you are reading the assembler and 
when you encounter somthing you do not understand you trigger a mail
and then stop looking at it.

I looked myself at the curptr and could not see where gr6 is assigned,
but if I really wanted to know then I would grab another cup
of coffee and look closer.
And when I found out myself I would know more for next time,
and I would reply with the answer.
Just sitting and waitng is not the way forward with this stuff.

So I encourage you to stir at the code for some more hours.
and maybe try to patch it and see if it changes behaviour.

And when you find out please send a patch adding a comment
so the next person does not have to spend 20 hours to understand it.

Good luck,

	Sam

Re: help about trap_setup..

[David Miller]

From: Bob <bo-liu@hotmail.com>
Date: Fri, 12 Dec 2008 17:02:36 +0800

> 
> Still no answer...

Nobody is obligated to answer your questions.  And that really means
nobody.

And I personally am in the mountains trying to enjoy some time off.
So it is very unpleasant for me to see something like this! :-/

I've had enough and personally I'm not going to anwer any of your
sparc questions.

Sorry.

RE: help about trap_setup..

[Bob]

   I am so sorry for that.And I found the answer by myself after reading the code 
 
more and more. 
 
   Thanks for Sam's suggestion. I am blush for my lazy.

   But i am not intentionally,davem !  I will try my best to corrct my mistakes. Such things 
 
won't happen again.
 
   Sorry again for that! Hoping you guys forgive me...
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