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Date: Tue, 23 Feb 2010 18:55:01 +0100
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From: Christoffer Dall <christofferdall@christofferdall.dk>
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Subject: [Qemu-devel] ARM: RealView boot problem
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To: qemu-devel@nongnu.org

I am trying to emulate ARMv6 on QEMU and cannot get past the early
kernel boot process. I wish to emulate the arm1136 cpu on the
realview-eb platform.

The config file for the kernel and my binaries can be found here:
http://www.cs.columbia.edu/~cdall/qemu-realview.tar.gz

To configure and compile qemu, I use the following command:
# ./configure --target-list=arm-softmmu
# make

I am using the stable-0.12 branch on commit
307331a42a39b46487f8f4356eaa943101f6af4e

To run qemu, I use this command:
# qemu-system-arm -M realview-eb -cpu arm1136 -kernel
~/src/linux-arm/arch/arm/boot/zImage -nographic -append
"console=ttyAMA0 debug initcall_debug"

I know that I need a file system to boot, but I should at least get
kernel printout here right?

I've tracked the issue to occur in a ldrex instruction, which
generates a data abort:
start_kernel()
 -> boot_cpu_init()
    -> set_cpu_online(cpu, true)
        -> cpumask_set_cpu(...)
            -> set_bit()
                -> _set_bit_le()
                     ....
                     ldrexb   r2, [r1]

The instruction is in arch/arm/lib/bitops.h:8

I tried mocking around quite a bit in the kernel config, but got nowhere.

Any help is greatly appreciated here.


Thanks!

Regards,
Christoffer Dall