On Thu, 24 Apr 2025 at 09:57, Zhang Chen <zhangc...@gmail.com> wrote: > > On Thu, Apr 3, 2025 at 10:23 AM Zhang Chen <zhangc...@gmail.com> wrote: > > > > On Thu, Apr 3, 2025 at 2:43 AM Richard Henderson > > <richard.hender...@linaro.org> wrote: > > > > > > On 4/2/25 06:54, Zhang Chen wrote: > > > > Because of the CONFIG_TCG auto enabled, the cpu type "cortex-a15" > > > > is mistakenly set to the default AARCH64 target. > > > > > > This is the correct backward compatible setting. > > > In essence, it means that you *must* supply a -cpu argument. > > > > > > > > > > If the "-cpu" is required, the VM should not be started without this > > argument. > > If yes, I will skip this patch and submit another one to make QEMU > > refuse to start without this parameter. > > > > Ping... and let me explain this status, it is not just for the default value. > 1. The cpu type "cortex-a15" is not the correct backward compatible > setting for AARCH64 target. > The ARM cortex-a15 is a 32 bit CPU based on ARMv7-A architecture. It > can not boot for AARCH64 target. > For example, the Apple M silicon can not boot with the default -cpu value.
'qemu-system-aarch64' doesn't mean "I want an AArch64 CPU", it just means that you can select AArch64 machines and CPUs. Almost all command lines that work with qemu-system-arm also do the same thing if run with qemu-system-aarch64. So in this case, "qemu-system-aarch64 -M virt" does the same as "qemu-system-arm -M virt", including the CPU type selected. The Cortex-A15 is now very rarely what anybody wants, but we keep it this way to avoid breaking existing users' command lines. (It works fine if you pass it a 32-bit guest kernel.) thanks -- PMM
