* [U-Boot-Users] how does stack work?
@ 2004-07-27 14:33 Seingier François-Xavier
2004-07-27 17:31 ` Kenneth Johansson
0 siblings, 1 reply; 3+ messages in thread
From: Seingier François-Xavier @ 2004-07-27 14:33 UTC (permalink / raw)
To: u-boot
hello,
I'm trying to understand how the initial stack works on a ppc4xx. According to start.S this is how the layout looks to me:
___________
| |
| |
| |
| gd_t |
|___________|
| 0 |
|___________|
| 0 |
|___________|<-+
| reset_vec | |
SP ->|___________| |
| |--+
|___________|<-+
| | |
|___________| |
| |--+
|___________|
| ... |
I can't figure out precisely how the last stack frame works:
- /* clear final stack frame so that */
/* stack backtraces terminate cleanly */
I'm not sure to understand the "terminate cleanly".
- why will the reset_vec be used in case of a stack underflow?
I tried to find an answer in the "PowerPC compiler writer's guide" about the ABI, but I am not even sure gcc uses an AIX or System V implementation...
If somebody could explain how this works in details, I would be very grateful (or point me to the right doc)
Thanks in advance
Fran?ois-Xavier SEINGIER
^ permalink raw reply [flat|nested] 3+ messages in thread* [U-Boot-Users] how does stack work?
2004-07-27 14:33 [U-Boot-Users] how does stack work? Seingier François-Xavier
@ 2004-07-27 17:31 ` Kenneth Johansson
0 siblings, 0 replies; 3+ messages in thread
From: Kenneth Johansson @ 2004-07-27 17:31 UTC (permalink / raw)
To: u-boot
Seingier Fran?ois-Xavier wrote:
>hello,
>I'm trying to understand how the initial stack works on a ppc4xx. According to start.S this is how the layout looks to me:
> ___________
> | |
> | |
> | |
> | gd_t |
> |___________|
> | 0 |
> |___________|
> | 0 |
> |___________|<-+
> | reset_vec | |
>SP ->|___________| |
> | |--+
> |___________|<-+
> | | |
> |___________| |
> | |--+
> |___________|
> | ... |
>
>I can't figure out precisely how the last stack frame works:
>- /* clear final stack frame so that */
> /* stack backtraces terminate cleanly */
>I'm not sure to understand the "terminate cleanly".
>
>
Some debug tool that get confused ??
>- why will the reset_vec be used in case of a stack underflow?
>I tried to find an answer in the "PowerPC compiler writer's guide" about the ABI, but I am not even sure gcc uses an AIX or System V implementation...
>
>
You can not return from the first function but for some unknown reason
you do that what should happen ?? a reboot is probably as good as anything.
The ABI for u-boot is eabi
ftp://ftp.funet.fi/pub/mirrors/sourceware.cygnus.com/pub/binutils/ppc-docs/
^ permalink raw reply [flat|nested] 3+ messages in thread
* [U-Boot-Users] how does stack work?
@ 2004-07-27 14:56 Seingier François-Xavier
0 siblings, 0 replies; 3+ messages in thread
From: Seingier François-Xavier @ 2004-07-27 14:56 UTC (permalink / raw)
To: u-boot
sorry I did not put the SP at the right place on the figure ;)
^ permalink raw reply [flat|nested] 3+ messages in thread
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2004-07-27 14:33 [U-Boot-Users] how does stack work? Seingier François-Xavier
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