linux-kernel - Re: [PATCH v2 01/17] x86/cpu: create Dhyana init file and register new cpu

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Date:   Tue, 24 Jul 2018 20:14:29 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Pu Wen <puwen@...on.cn>, tglx@...utronix.de, bp@...en8.de,
        thomas.lendacky@....com, mingo@...hat.com, hpa@...or.com,
        peterz@...radead.org, tony.luck@...el.com, rkrcmar@...hat.com,
        boris.ostrovsky@...cle.com, jgross@...e.com, rjw@...ysocki.net,
        lenb@...nel.org, viresh.kumar@...aro.org, mchehab@...nel.org,
        trenn@...e.com, shuah@...nel.org, JBeulich@...e.com, x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        kvm@...r.kernel.org, xen-devel@...ts.xenproject.org
Subject: Re: [PATCH v2 01/17] x86/cpu: create Dhyana init file and register
 new cpu_dev to system

On 23/07/2018 15:20, Pu Wen wrote:
> Add x86 architecture support for new processor Hygon Dhyana Family 18h.
> Rework to create a separated file(arch/x86/kernel/cpu/hygon.c) from the
> AMD init one(arch/x86/kernel/cpu/amd.c) to initialize Dhyana CPU. In
> this way we can remove old AMD architecture support codes from Hygon
> code path and generate a clear initialization flow for Hygon processors,
> it also reduce long-term maintenance effort.
> Also add hygon.c Maintainer information in accordance.
> 
> To identify Hygon processors, add a new vendor type X86_VENDOR_HYGON(9)
> for system recognition.
> 
> To enable Hygon processor config, add a separated Kconfig entry(CPU_SUP_
> HYGON) for Dhyana CPU in kernel config setup.

If Hygon processors are currently the same as AMD, I don't see the point
in creating a new file just for them.  Likewise for example in patch 6


+	case X86_VENDOR_HYGON:
+		ideal_nops = p6_nops;
+		return;
+
 	case X86_VENDOR_AMD:
 		if (boot_cpu_data.x86 > 0xf) {
 			ideal_nops = p6_nops;

Should only need to add "case X86_VENDOR_HYGON:".  Or you could even
reuse X86_VENDOR_AMD.

Paolo