[Qemu-devel] Linux kernel image for Emulator - Regd.

[Qemu-devel] Linux kernel image for Emulator - Regd.

[Sudheer Papothi]

Hi

I am newbie to l inux porting. I was trying to port linux on a new ARM 
platform.

Before doing that I would like to debug the same using ARM emulator.

So, I tried the arm-linux image (cpu type: arm1136) that I built, on 
qemu.  But i am getting the following error.

$ qemu-system-arm -cpu arm1136 -kernel zImage -initrd arm_root.img 
-nographic -append "console=ttyAMA0"

qemu: fatal: Bad mode 0

R00=0018fc7c R01=00000000 R02=e3a131a4 R03=00000000
R04=000131a4 R05=0018fc7c R06=e18c8da9 R07=0018fcf4
R08=00008000 R09=0000000c R10=0000000d R11=00198fc4
R12=00000000 R13=00198fa8 R14=00010a30 R15=00008000
PSR=000001d3 ---- A svc32
s00=00000000(       0) s01=00000000(       0) d00=0000000000000000(       0)
s02=00000000(       0) s03=00000000(       0) d01=0000000000000000(       0)
s04=00000000(       0) s05=00000000(       0) d02=0000000000000000(       0)
s06=00000000(       0) s07=00000000(       0) d03=0000000000000000(       0)
s08=00000000(       0) s09=00000000(       0) d04=0000000000000000(       0)
s10=00000000(       0) s11=00000000(       0) d05=0000000000000000(       0)
s12=00000000(       0) s13=00000000(       0) d06=0000000000000000(       0)
s14=00000000(       0) s15=00000000(       0) d07=0000000000000000(       0)
s16=00000000(       0) s17=00000000(       0) d08=0000000000000000(       0)
s18=00000000(       0) s19=00000000(       0) d09=0000000000000000(       0)
s20=00000000(       0) s21=00000000(       0) d10=0000000000000000(       0)
s22=00000000(       0) s23=00000000(       0) d11=0000000000000000(       0)
s24=00000000(       0) s25=00000000(       0) d12=0000000000000000(       0)
s26=00000000(       0) s27=00000000(       0) d13=0000000000000000(       0)
s28=00000000(       0) s29=00000000(       0) d14=0000000000000000(       0)
s30=00000000(       0) s31=00000000(       0) d15=0000000000000000(       0)
FPSCR: 00000000
Aborted

So, I tried the linux image ( cpu: arm1136 ) which is already working on 
our platform, on qemu. Here, even in this case, the above error is 
reproduced.

Can anyone please let me know what changes are required in linux kernel 
to run it on emulator (i.e., qemu).

It would be great if some one points to the documentation of linux 
kernel compilation for emultors (if anything specifically required) 
other than normal compilation.

I tried the arm test binary present in Qemu website and it is working fine.

-- 
Thanks & Regards
Sudheer

Re: [Qemu-devel] Linux kernel image for Emulator - Regd.

[Laurent Desnogues]

On Tue, Jun 24, 2008 at 11:32 AM, Sudheer Papothi
<sudheer.papothi@amd.com> wrote:
>
> qemu: fatal: Bad mode 0

Your kernel is probably writing some undefined mode in
the CPSR.  Most implementations will translate that to
another valid mode, qemu doesn't.


Laurent

Re: [Qemu-devel] Linux kernel image for Emulator - Regd.

[Salil Bijur]

On Tue, Jun 24, 2008 at 3:02 PM, Sudheer Papothi
<sudheer.papothi@amd.com> wrote:
> Hi
>
> I am newbie to l inux porting. I was trying to port linux on a new ARM
> platform.
>
> Before doing that I would like to debug the same using ARM emulator.
>
> So, I tried the arm-linux image (cpu type: arm1136) that I built, on qemu.
>  But i am getting the following error.
>

Which ARM machine has the kernel been built with?
Use the -m option to specify the machine such as integrator or
versatile. The kernel should be for that specific machine.

Salil

Re: [Qemu-devel] Linux kernel image for Emulator - Regd.

[Sudheer Papothi]

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Salil Bijur wrote:
> On Tue, Jun 24, 2008 at 3:02 PM, Sudheer Papothi
> <sudheer.papothi@amd.com> wrote:
>   
>> Hi
>>
>> I am newbie to l inux porting. I was trying to port linux on a new ARM
>> platform.
>>
>> Before doing that I would like to debug the same using ARM emulator.
>>
>> So, I tried the arm-linux image (cpu type: arm1136) that I built, on qemu.
>>  But i am getting the following error.
>>
>>     
>
> Which ARM machine has the kernel been built with?
> Use the -m option to specify the machine such as integrator or
> versatile. The kernel should be for that specific machine.
>
> Salil
>
>
>
>   
The machine type is not defined in machine list of qemu for arm1136. So, 
cpu type arm1136 is used instead with -cpu option.

-- 
Thanks & Regards
Sudheer




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Re: [Qemu-devel] Linux kernel image for Emulator - Regd.

[Sudheer Papothi]

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Laurent Desnogues wrote:
> On Tue, Jun 24, 2008 at 11:32 AM, Sudheer Papothi
> <sudheer.papothi@amd.com> wrote:
>   
>> qemu: fatal: Bad mode 0
>>     
>
> Your kernel is probably writing some undefined mode in
> the CPSR.  Most implementations will translate that to
> another valid mode, qemu doesn't.
>
>
> Laurent
>
>
>
>   

Thanks Laurent

ARM Linux kernel is built with arm-gnu-eabi  cross  compiler toolchain 
(from code sourcery).

I dont think this will be a problem (correct me if i am wrong). It 
creates normal zImage as well as uImage (with the help of mkimage )

Can you please brief the point /*"Most implementations will translate 
that to another valid mode, qemu does n't"*/

Can you please  suggest any other options to test/debug my basic linux 
kernel image as I dont have the real hardware yet.

-- 
Thanks & Regards
Sudheer




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Re: [Qemu-devel] Linux kernel image for Emulator - Regd.

[Laurent Desnogues]

On Tue, Jun 24, 2008 at 1:16 PM, Sudheer Papothi
<sudheer.papothi@amd.com> wrote:
> ARM Linux kernel is built with arm-gnu-eabi  cross  compiler toolchain (from
> code sourcery).
>
> I dont think this will be a problem (correct me if i am wrong). It creates
> normal zImage as well as uImage (with the help of mkimage )

The compiler should not be the problem (at least as long as you
are not targetting armv7 class processor).

> Can you please brief the point "Most implementations will translate that to
> another valid mode, qemu does n't"

If the lower 5 bits written to CPSR don't match valid modes,
most silicon will put another valid mode.  I can't say more, but
this is undocumented behaviour.  As an example (not tested
on realy HW), if you write 0 to the M field of CPSR it will get
translated of 0x10 = user mode. qemu doesn't do that, it just
aborts.

> Can you please  suggest any other options to test/debug my basic linux
> kernel image as I dont have the real hardware yet.

I don't get it, you said the kernel booted on real hardware...

Anyway according to your log your kernel is failing at its
very first instruction (pc = 0x8000).  Are you using a boot
loader?


Laurent

Re: [Qemu-devel] Linux kernel image for Emulator - Regd.

[Sudheer Papothi]

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>> Can you please  suggest any other options to test/debug my basic linux
>> kernel image as I dont have the real hardware yet.
>>     
>
> I don't get it, you said the kernel booted on real hardware...
>
> Anyway according to your log your kernel is failing at its
> very first instruction (pc = 0x8000).  Are you using a boot
> loader?
>
>
> Laurent
>
>
>
>   

Thanks Laurent

We have two linux kernel images in which one works on real hardware and 
the other image still does not have hardware.

We have to make the latter image ready before the hardware is available.

Can you please suggest any other options to test/debug the linux kernel 
image for which the hardware is not yet available.


-- 
Thanks & Regards
Sudheer




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