Re: [Xenomai] Adeos I-Pipe patch problem on vendor-specific kernel

From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
To: Wayne Warren <wwarren@emacinc.com>
Cc: xenomai@xenomai.org
Subject: Re: [Xenomai] Adeos I-Pipe patch problem on vendor-specific kernel
Date: Wed, 24 Oct 2012 20:05:04 +0200	[thread overview]
Message-ID: <50882DD0.3030902@xenomai.org> (raw)
In-Reply-To: <1351101328.25888.330.camel@ENG-09-LX.emacinc.com>

On 10/24/2012 07:55 PM, Wayne Warren wrote:
> 
>>
>> What you need is __ipipe_tsc_register to be called before any call to
>> __ipipe_tsc_update.
> 
> This breakpoint is definitely hit before the __ipipe_tsc_update
> breakpoint:
> 
> Breakpoint 8, __ipipe_tsc_register (info=0xc0634108) at /home/wayne/src/linux/linux-2.6.37-3517-xenomai/arch/arm/kernel/ipipe_tsc.c:45
> 45              switch(info->type) { 
> (gdb) bt                                                                                                                              
> #0  __ipipe_tsc_register (info=0xc0634108) at /home/wayne/src/linux/linux-2.6.37-3517-xenomai/arch/arm/kernel/ipipe_tsc.c:45          
> #1  0xc001121c in omap2_gp_timer_init () at /home/wayne/src/linux/linux-2.6.37-3517-xenomai/arch/arm/mach-omap2/timer-gp.c:274       
> #2  0xc000cae4 in time_init () at /home/wayne/src/linux/linux-2.6.37-3517-xenomai/arch/arm/kernel/time.c:163                          
> #3  0xc0008b5c in start_kernel () at /home/wayne/src/linux/linux-2.6.37-3517-xenomai/init/main.c:617                          
> #4  0x80008034 in ?? ()    
> 
> 
>>
>> __ipipe_tsc_get is supposed to be defined to be something like 0xffff0f40
> 
>    │0xc0052ca4 <__ipipe_tsc_update+88>      ldr    r3, [pc, #36]   ; 0xc0052cd0 <__ipipe_tsc_update+132>
>   >│0xc0052ca8 <__ipipe_tsc_update+92>      blx    r3                                                   
>    │0xc0052cac <__ipipe_tsc_update+96>      ldr    r3, [pc, #24]   ; 0xc0052ccc <__ipipe_tsc_update+128>    
> 
> (gdb) info reg r3                                                         
> r3             0xffff0f40       4294905664                                
> (gdb) disassemble 0xffff0f40                                              
> No function contains specified address.                                   
> (gdb) x 0xffff0f40                                                        
> 0xffff0f40:     0xe51f000c                                                
> (gdb) focus cmd                                                           
> Focus set to CMD window.                                                  
> (gdb) x /10                                                               
> 0xffff0f40:     0xe51f000c      0xe14f22dc      0xe5900000      0xe1520000
> 0xffff0f50:     0xe2a31000      0xe12fff1e      0xe1a00000      0xe1a00000
> 0xffff0f60:     0x00000000      0x00000000                                                                                                                   
> (gdb)                        
> 
> So it looks like maybe __ipipe_tsc_get is working as expected? 

Yes, the debugger can not know what is at 0xffff0f40 because the code
copied there is not known at compilation (though you can run disass
*0xffff0f40, this should work). __ipipe_tsc_register does copy the
actual code, but before __ipipe_tsc_register copies the code, the code
there simply returns r0 and r1 set to 0.

You should try and put a breakpoint at 0xffff040 to see what address is
invalid. Maybe the counter virtual address is invalid, or the access to
the timer register because the timer is not enabled yet at hardware level.

>                       
>>
>> Or apply the following patch:
>> http://git.xenomai.org/?p=ipipe-gch.git;a=commitdiff;h=42dd9056983cb6f65b6a336363f2f08f4426625a;hp=3b51cebda0b0d0123cb61b6ec07ecb62f293a528
> 
> I will try this out, thanks!

It will probably not fix this issue, but it is better to start from that
code anyway.

-- 
					    Gilles.