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Re: Réf. : Compiling a 2.6 kernel for Mips

To: Florian DELIZY <florian.delizy@sagem.com>
Subject: Re: Réf. : Compiling a 2.6 kernel for Mips
From: Yoann Allain <yallain@avilinks.com>
Date: Wed, 28 Sep 2005 15:38:33 +0200
Cc: linux-mips@linux-mips.org
In-reply-to: <OF6AB06D9F.A4F86C60-ONC125708A.003730C5-C125708A.00479A09@sagem.com>
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Here is the function putPromChar in which I have the problem:

80101e70 <putPromChar>:
80101e70:       3c028039        lui     $v0,0x8039
80101e74:       244519f0        addiu   $a1,$v0,6640
80101e78:       8ca30014        lw      $v1,20($a1)
80101e7c:       00042600        sll     $a0,$a0,24
80101e80:       27bdfff0        addiu   $sp,$sp,-16
80101e84:       00043603        sra     $a2,$a0,24
80101e88:       10600012        beqz    $v1,80101ed4 <putPromChar+0x64>
80101e8c:       00001025        move    $v0,$zero
80101e90:       8ca20004        lw      $v0,4($a1)
80101e94:       3c038036        lui     $v1,0x8036
80101e98:       8c64c9a0        lw      $a0,-13920($v1)
80101e9c:       2442001c        addiu   $v0,$v0,28
80101ea0:       00822021        addu    $a0,$a0,$v0
80101ea4:       00000000        nop
80101ea8:       8c820000        lw      $v0,0($a0)
80101eac:       30420020        andi    $v0,$v0,0x20
80101eb0:       1040fffd        beqz    $v0,80101ea8 <putPromChar+0x38>
80101eb4:       3c028039        lui     $v0,0x8039
80101eb8:       8c4319f4        lw      $v1,6644($v0)
80101ebc:       3c048036        lui     $a0,0x8036
80101ec0:       8c82c9a0        lw      $v0,-13920($a0)
80101ec4:       24630004        addiu   $v1,$v1,4
80101ec8:       00431021        addu    $v0,$v0,$v1
80101ecc:       ac460000        sw      $a2,0($v0)
80101ed0:       24020001        li      $v0,1
80101ed4:       03e00008        jr      $ra
80101ed8:       27bd0010        addiu   $sp,$sp,16
80101edc:       00000000        nop

with WinMon (bootloader) I get this (this is perhaps more readable...):

[80101e70] 3c028039 lui         r2,0x8039               putPromChar
[80101e74] 244519f0 addiu       r5,r2,0x19f0
[80101e78] 8ca30014 lw          r3,0x0014(r5)
[80101e7c] 00042600 sll         r4,r4,24
[80101e80] 27bdfff0 addiu       r29,r29,0xfff0
[80101e84] 00043603 sra         r6,r4,24
[80101e88] 10600012 beq         r3,r0,0x0012
[80101e90] 8ca20004 lw r2,0x0004(r5) --> in 2.6 it reads 0 at address r5 + 0x4 [80101e94] 3c038036 lui r3,0x8036
[80101e98] 8c64c9a0 lw          r4,0xc9a0(r3)           --> in 2.6 it reads 0 
at adress r3 + 0xc9a0
[80101e9c] 2442001c addiu       r2,r2,0x001c
[80101ea0] 00822021 addu        r4,r4,r2                ==> in 2.4 it returns 
bf010f1c in r4
[80101ea8] 8c820000 lw          r2,0x0000(r4)

* Exception 0x02 (user) : TLB (load or instruction fetch) *
* in address: 80101ea8
ClockDiv2+0xe38:
[80101ea8] 8c820000 lw          r2,0x0000(r4)


r0(zero): 00000000 r1(AT)  : 1000fc00 r2(v0)  : 0000001c r3(v1)  : 80360000
r4(a0)  : 0000001c r5(a1)  : 803919f0 r6(a2)  : 0000000d r7(a3)  : 8038df8c

I hope this will help and many thanks for your help!

Yoann



Florian DELIZY wrote:





> Hi,

> I am no more a newbie but I still need some help to build kernels :
> I am working on the Wintegra Evaluation Board (WEB777) and I used the
> 2.4 kernel Wintegra gave me with the patch for that board.
> I tried to adapt the patch for the 2.6 kernel but it doesn't work. I
> traced the kernel to find it crashed very early before displaying anything.
> In fact the host processor makes an address and tries to read it but
> this makes an exception :

> * Exception 0x02 (user) : TLB (load or instruction fetch) *
> * in address: 80101ea8
> ClockDiv2+0xe38:
> [80101ea8] 8c820000 lw          r2,0x0000(r4)


> r0(zero): 00000000 r1(AT) : 1000fc00 r2(v0) : 0000001c r3(v1) : 80360000 > r4(a0) : 0000001c r5(a1) : 803919f0 r6(a2) : 0000000d r7(a3) : 8038df8c

That would help a lot if you could objdump your kernel and give us 10 instructions before (at least)
and 10 instructions after it, you could try an :

mips-linux-objdump -DSz vmlinux | grep -U 20 '^\[80101ea8\]'

and send the output (that should ouput around 20 lines (which will hopefully contain some C code also, assuùing that you compiled the code with debug informations. Moreover you can also tell us in which
symbol (function) is located the address 0x80101ea8.


> I think this is a problem of host processor misconfiguration, but don't
> find out exactly what it is... To make the address in R4, the processor
> reads some zeroes where in 2.4 kernel, it doesn't and the address read
> in 2.4 is something like 0xbf010f1c.
> I don't know if this can help but here are the few functions before crash:

> kernel_entry
>    J start_kernel
>             cpu_probe() (WEB777 patch)
>             prom_init() (WEB777 patch)
>                   setup_prom_printf() (WEB777 patch)
>                   wds_prom_printf() (WEB777 patch)
>                            putPromChar() (WEB777 patch)
>                            --> CRASH

You should also start to figure out which variable/pointer anything is consulted to get this adress (0x0000001c)
which might then help to understand you're problem.

Regards

Florian Delizy


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