linux-kernel - Re: [PATCH 2/3] x86: Get TSC frequency from VMware hypervisor.

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Message-ID: <48FE00A9.6010400@zytor.com>
Date:	Tue, 21 Oct 2008 09:17:45 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	akataria@...are.com
CC:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	the arch/x86 maintainers <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Daniel Hecht <dhecht@...are.com>
Subject: Re: [PATCH 2/3] x86: Get TSC frequency from VMware hypervisor.

Alok Kataria wrote:
> 
> Hi hpa,
> 
> Do you mean we should have a x86_hyper_vendor field in cpuinfo_x86 ? 
> Even with that, i think we will have to differentiate between each of
> the hypervisors, as each of the hypervisor implementation differs in how
> they provide the TSC frequency. 
> 
> So we would end up with code like,
> 	if (boot_cpu.x86_hyper_vendor == VMWARE)
> 		get_frequency_vmware_way();
> 	if (boot_cpu.x86_hyper_vendor == XXX)
> 		get_frequency_XXX_way();
> 
> I agree that having a field in the cpu structure will make sure that we
> don't end up calling vmware_platform multiple times, but does it help in
> this particular situation ?
> 
> Let me know if you meant something else.
> 

That's exactly what I mean.  I want the detection centralized, and no, 
with only one user it doesn't make much difference, but there won't be 
just one user.

	-hpa
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