Re: [PATCH 2/2] hw/riscv/virt.c: change default CPU to 'max'

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 7/4/25 01:31, Alistair Francis wrote:
> On Sat, Apr 5, 2025 at 9:02 AM Richard Henderson
> <richard.henderson@linaro.org> wrote:
>>
>> On 4/4/25 08:27, Daniel Henrique Barboza wrote:
>>> Using 'max' as
>>> default CPU is done by other QEMU archs like aarch64 so we'll be more
>>> compatible with everyone else.
>>
>> This isn't true.  qemu-system-aarch64 -M virt defaults to cortex-a15 (for hysterical
>> raisins), which is completely and totally useless.  Which means that one must always pass
>> a -cpu option to qemu-system-aarch64.
>>
>> Moreover, -cpu max has zero migration guarantees, so anyone who wants to be able to
>> reliably migrate is encouraged to use a real cpu model.
>>
>> I suppose, for throwaway VMs, -cpu max is a decent default.  But there's a lot to be said
>> for not specifying a default at all.
> 
> I agree. If we aren't going to specify a default machine, why specify
> a default CPU?
> 
> It probably makes sense to deprecate the default CPU for non-vendor
> machines and then force users to pick their own CPU. That should start
> in 10.1 so it's a release offset from the removal of the default
> machine.

IMHO this is the sanest things to do.

> Then maybe think about even removing rv32/rv64 CPUs and push people to
> the profiles, as it's a lot clearer what they are getting.
> 
> Alistair
> 
>>
>>
>> r~
>>
>