Sometimes, issues are due to bugs in the OVMF firmware. They typically manifest themselves as hangs on boot, and are sometimes triggered by QEMU updates.
In such cases, a good first debug attempt is to build the latest firmware from source.
Prepare the machine:
sudo apt-get install build-essential uuid-dev iasl git gcc-5 nasm
Clone the repository and change path:
git clone --recursive https://github.com/tianocore/edk2.git
cd edk2
Compile and build the tools:
make -C BaseTools
export EDK_TOOLS_PATH=$(pwd)/BaseTools
source edksetup.sh BaseTools
Configure the build, in this case for an X64 target:
perl -i -pe 's/^(ACTIVE_PLATFORM).* /$1 = OvmfPkg\/OvmfPkgX64.dsc/x' Conf/target.txt
perl -i -pe 's/^(TOOL_CHAIN_TAG).* /$1 = GCC5/x' Conf/target.txt
perl -i -pe 's/^(TARGET_ARCH).* /$1 = X64/x' Conf/target.txt
Build:
build
Enjoy!:
$ ls -1 Build/OvmfX64/DEBUG_GCC5/FV/OVMF_*.fd
Build/OvmfX64/DEBUG_GCC5/FV/OVMF_CODE.fd
Build/OvmfX64/DEBUG_GCC5/FV/OVMF_VARS.fd
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QEMU 4.0 suffers from a regression, which causes both host and guest to hang on VM start (see [https://bugs.launchpad.net/qemu/+bug/1826422]).
In order to workaround this problem, add kernel-irqchip=on to the -machine option, for example:
-machine q35,accel=kvm,mem-merge=off,kernel-irqchip=on
QEMU 3.x/4.1+ users don't need this option.