Re: [Qemu-devel] Problem with translating on ARM and Qemu beginner question

[Gauresh Rane]

The problem was indeed with the stack. It's just doing a fake push, that is the 
environment variables are updated but the the variables are not loaded into the 
stack. I see the values in the stack always are zero.

I am trying to figure out what might be the reason for this.

Thanks for the help,

Regards,

Gauresh Rane
Grad Student
CS Department
UCLA

----- Original Message -----
From: "Peter Maydell" <address@hidden>
To: "Max Filippov" <address@hidden>
Cc: "Gauresh Rane" <address@hidden>, address@hidden
Sent: Friday, November 25, 2011 7:40:52 AM
Subject: Re: [Qemu-devel] Problem with translating on ARM and Qemu beginner 
question

On 25 November 2011 15:35, Max Filippov <address@hidden> wrote:
>> Breakpoint 7, cpu_arm_exec (env=0x102033200) at ~/qemu-0.15.0/cpu-exec.c:557
>> 557                         next_tb = tcg_qemu_tb_exec(env, tc_ptr);
>> (gdb) p/x env->regs
>> $13 = {0x4002c00c, 0x20, 0x4, 0x0, 0x0, 0x0, 0x40000, 0x0, 0x0, 0x0, 0x0, 
>> 0x0, 0x30, 0x10007fa8, 0x560d, 0x560c}
>> (gdb) s
>> 558                         if ((next_tb & 3) == 2) {
>> (gdb) p/x env->regs
>> $14 = {0x10048000, 0x20, 0x4, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 
>> 0x30, 0x10007fb8, 0x560d, 0x0}
>>
>> How to check access to unallocated memory? It's not seg faulting.
>
> 290 0000042c <_init>:
> 291  42c:   b5f8        push    {r3, r4, r5, r6, r7, lr}
>
> set breakpoint here and see with x/6wx $sp whether saved register values are 
> good.

To clarify this a bit: that means "set a breakpoint in an ARM gdb attached
to qemu's gdb-stub interface". That gdb will see the view of the guest
CPU, whereas connecting an x86 gdb directly to qemu you're looking at
qemu's internal data structures, which can be more confusing.

-- PMM