Subject: Re: Trace

From: Sébastien Chrétien<[email-masked]>
Date: Mon, 01 Sep 2008 18:33:35 +0200

Thanks for your answer.
Your analyse of ttys is very well. It was not my answer. All adresses in 
system.map begin with 0xc... So I think it is the case for ttys too.

I found the mistake. It came from my board_device function in struct 
console(console ->device). It didn't change the value of the parameter 
int* index.
So Linux loaded a tty_structure which was in tiny_ttys[-1]

console.h is not very well documented about this.

Thanks
Sébastien Chrétien

Jenkins, Clive a écrit :
>>  Why can't tty have value 0x57555541 ?
>>     
> To answer my own question, because it ends in 1 and is not word-aligned!
>
> -----Original Message-----
> From: linuxppc-dev-bounces+clive.jenkins=[email-masked] [mailto:linuxppc-dev-bounces+clive.jenkins=[email-masked]] On Behalf Of Jenkins, Clive
> Sent: 01 September 2008 14:54
> To: Sébastien Chrétien
> Cc: [email-masked]
> Subject: RE: Trace
>
> I'm not sure that is a failure. Why can't tty have value 0x57555541 ?
>
> I think the code in tty_io.c initialises driver->ttys and you shouldn't need to do anything in your driver.
>  
> If you are not already aware, a useful way to explore kernel code is to use LXR:
> http://lxr.linux.no/linux+v2.6.26/include/linux/tty_driver.h#L212
> This may help you understand the tty code.
>  
> Good luck!
>  
> ________________________________
>
> From: Sébastien Chrétien [mailto:[email-masked]] 
> Sent: 01 September 2008 13:25
> To: Jenkins, Clive
> Cc: [email-masked]
> Subject: Re: Trace
>
>
> I found where is the failure with your advices 
> In init_dev (tty_io.c), init_dev calls "tty = driver->ttys[idx]"
> after this call, tty value is : tty = 0x57555541
>
> Have I to initialize driver->ttys in my driver. If yes, how have I to Initialize this ?
>
> The driver tty is used in order to have a console on my serial port.
> Thanks for your help
>
>
>
> 2008/9/1, Jenkins, Clive <[email-masked]>: 
>
> 	The instruction that caused the fault is at this address:
> 	
> 	> NIP [c0110ddc] init_dev+0x2bc/0x584
> 	
> 	
> 	The hex value of the instruction is also highlighted between <> here:
> 	
> 	> Instruction dump:
> 	> 7d808120 4e800020 7c832378 4bfa9ea9 7c7f1b79 418201f0 a81e0062 2f800001
> 	> 409efd98 83ff00d0 2c1f0000 4182fd90 <801f00b8> 70090080 408201b0 801e0060
> 	
> 	
> 	Disassemble your kernel and look at offset 0x2BC relative to the label init_dev
> 	
> 	________________________________
> 	
> 	From: linuxppc-dev-bounces+clive.jenkins=[email-masked] [mailto:linuxppc-dev-bounces+clive.jenkins <mailto:linuxppc-dev-bounces%2Bclive.jenkins> =[email-masked]] On Behalf Of Sébastien Chrétien
> 	Sent: 01 September 2008 10:16
> 	To: [email-masked]
> 	Subject: Trace
> 	
> 	
> 	
> 	Hello,
> 	
> 	I am triying to write a tty_driver under ppc. And I get a kernel panic.
> 	Can somebody explain me how finding the source of the error with a kernel panic trace :
> 	thanks
> 	
> 	Unable to handle kernel paging request for data at address 0x575555f9
> 	Faulting instruction address: 0xc0110ddc
> 	Oops: Kernel access of bad area, sig: 11 [#1]
> 	Modules linked in:
> 	NIP: c0110ddc LR: c011118c CTR: 00000000
> 	REGS: cf01bcb0 TRAP: 0300   Not tainted  (2.6.26)
> 	MSR: 00009032 <EE,ME,IR,DR>  CR: 44002022  XER: 20000000
> 	DAR: 575555f9, DSISR: 40000000
> 	TASK = cf01c000[1] 'swapper' THREAD: cf01a000
> 	GPR00: 0000000c cf01bd60 cf01c000 cf04c300 ffffffff cf01bdbc 00000000 c01d0000
> 	GPR08: 00001249 fffffffc 00000000 cf000420 84002022 00000000 10000b00 007fff00
> 	GPR16: 0fffa1d0 00000000 00000004 cf01bdbc 007ffec0 00000000 00000000 00800000
> 	GPR24: 00000000 c01b7650 00000002 c01d0000 ffffffff ce4a6700 cf04c300 57555541
> 	NIP [c0110ddc] init_dev+0x2bc/0x584
> 	LR [c011118c] tty_open+0xe8/0x3e0
> 	Call Trace:
> 	[cf01bd60] [cf01bd78] 0xcf01bd78 (unreliable)
> 	[cf01bdb0] [c011118c] tty_open+0xe8/0x3e0
> 	[cf01bde0] [c00742c8] chrdev_open+0x114/0x1b0
> 	[cf01be10] [c006fb5c] __dentry_open+0x190/0x2e8
> 	[cf01be40] [c006fdac] nameidata_to_filp+0x38/0x70
> 	[cf01be60] [c007bc60] do_filp_open+0x200/0x7d0
> 	[cf01bf10] [c00700b4] do_sys_open+0x74/0x114
> 	[cf01bf40] [c0003c94] init_post+0x34/0x258
> 	[cf01bf60] [c019ca64] kernel_init+0x258/0x270
> 	[cf01bff0] [c0011b3c] kernel_thread+0x44/0x60
> 	Instruction dump:
> 	7d808120 4e800020 7c832378 4bfa9ea9 7c7f1b79 418201f0 a81e0062 2f800001
> 	409efd98 83ff00d0 2c1f0000 4182fd90 <801f00b8> 70090080 408201b0 801e0060
> 	---[ end trace b7795a387aeb7786 ]---
> 	Kernel panic - not syncing: Attempted to kill init!
> 	allocation failed: out of vmalloc space - use vmalloc=<size> to increase size.
> 	
> 	
>
>
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