QEMU debugging:: Warning:TCG doesn't support requested feature: CPUID.01H:ECX

skytree picture skytree · Oct 20, 2017 · Viewed 21.1k times · Source

I want to use QEMU to debug my compiled kernel linux-4.13.4 on Ubuntu 16.04.3 LTS

I follow the following steps:

1 install qemu

sudo apt-get install qemu

2 run qemu

qemu-system-x86_64 -s -S -kernel /home/wxf/kernelSources/linux-4.13.4/arch/x86_64/boot/bzImage -initrd /boot/initrd.img-4.13.4

Note:

-s shorthand for -gdb tcp::1234

-S freeze CPU at startup (use 'c' to start execution)

But I get the following warning:

warning: TCG doesn't support requested feature: CPUID.01H:ECX.vmx [bit 5]

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The terminal stops there and I cannot input other commands.

The QEMU window pops up when I run it but it is stopped.

enter image description here

So, my question is

How to eliminate the warning and is it normal(since it is not an error information)?

Answer

Anatoly Trosinenko picture Anatoly Trosinenko · Oct 21, 2017

Frankly speaking, I don't know how to handle that warning, can it be ignored or have you to do something with it. But I suppose the main problem is that you cannot run the VM. If so, you need to properly determine where to enter that c to start the VM. :)

QEMU has several graphical interfaces (and AFAIK can even be run in plain console). Suppose we have identical defaults for which UI to use (probably, the GTK one). When I run similar command (qemu-system-x86_64 -s -S -kernel ...), I can switch to the monitor console of QEMU by pressing Ctrl+Alt+2 (just 2, not F2). There I press c (and Enter, it seems to behave like regular terminal) and then switch to the VM display by Ctrl+Alt+1.

QEMU monitor console