Re: [PATCH v2 3/4] target/i386: Introduce Zhaoxin Shijidadao-Client CPU model

[Zhao Liu <zhao1.liu@intel.com>]

> >> As background, current Zhaoxin CPUs implement several CPUID.(EAX=0xC0000001,
> >> ECX=0):EDX feature bits that are not yet defined in the Linux kernel, for
> >> example SM2/SM2_EN, SM3/SM4 and their enable bits, PARALLAX/PARALLAX_EN,
> >> TM3/TM3_EN, RNG2/RNG2_EN, PHE2/PHE2_EN, and RSA/RSA_EN.
> >>
> >> We previously tried to upstream all these extra feature bits in one
> >> patch(https://lore.kernel.org/all/20230414095334.8743-1-TonyWWang-oc@zhaoxin.com/),
> >> but the maintainer rejected it because there was no in-tree code using these
> >> features yet. So our current plan is to add the CPUID bits together with real
> >> kernel users step by step.
> > 
> > I see. I think it's enough to document missing CPUIDs in comment.
> > 
> 
> Would the following comment be acceptable?
> 
> /*
>  * missing: SM2/SM2_EN, CCS/CCS_EN, PARALLAX/PARALLAX_EN,
>  * TM3/TM3_EN, RNG2/RNG2_EN, PHE2/PHE2_EN, RSA/RSA_EN
>  */

Yes, look good to me.

> Do you think I should also include the lore link in the commit message/cover
> letter for additional context?

Yes, mentioning the link in commit message is good. More information is
helpful.

> > Could we make Shijidadao-Client as a v2 of Shijidadao-Server, and create an
> > alias for this v2?
> > 
> > .alias = "Shijidadao-Client"
> > 
> > Then we could rename Shijidadao-Server to Shijidadao, and its v2 is for
> > client.
> > 
> >> This is also aligned with how QEMU models other vendors' micro-architectures
> >> where client and server products have slightly different feature sets.
> > 
> > The main use case for CPU models is to easy migration across mixed CPU
> > clusters [*]. So, IMO, not all products require a model.
> 
> For the CPU model naming/versioning, my plan is:
> The current Shijidadao will be equivalent to the old Shijidadao-Client-v2, drop
> the old Shijidadao-Client-v1 according to your advice, Shijidadao-v1 will have
> the alias Shijidadao-Client, and Shijidadao-v2 will have the alias
> Shijidadao-Server.

Migration should have more use cases for the server. Personally, I feel
using the server version as the base model might be more convenient?
Anyway, it's up to you. Overall, these are fine for me.

Thanks,
Zhao