From: "Jan Beulich" <JBeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH v3 15/28] x86/cpu: Sysctl and common infrastructure for levelling context switching
Date: Tue, 22 Mar 2016 10:16:35 -0600 [thread overview]
Message-ID: <56F17DF302000078000DF4D0@prv-mh.provo.novell.com> (raw)
In-Reply-To: <56F16B80.9000908@citrix.com>
>>> On 22.03.16 at 16:57, <andrew.cooper3@citrix.com> wrote:
> On 21/03/16 16:23, Jan Beulich wrote:
>>>>> On 15.03.16 at 16:35, <andrew.cooper3@citrix.com> wrote:
>>> --- a/xen/arch/x86/cpu/common.c
>>> +++ b/xen/arch/x86/cpu/common.c
>>> @@ -36,6 +36,12 @@ integer_param("cpuid_mask_ext_ecx",
>>> opt_cpuid_mask_ext_ecx);
>>> unsigned int opt_cpuid_mask_ext_edx = ~0u;
>>> integer_param("cpuid_mask_ext_edx", opt_cpuid_mask_ext_edx);
>>>
>>> +unsigned int __initdata expected_levelling_cap;
>> Especially for an __initdata item to be non-static, its use(s) should
>> be visible in a patch adding such a variable.
>
> From the commit message:
>> This interface will currently report no capabilities. This change is
>> scaffolding for future patches, which will introduce detection and switching
>> logic, after which the interface will report hardware capabilities
> correctly.
>
> This is specifically to reduce the complexity of the following patches.
> How much more clearly do you want this stating?
The problem isn't that this wasn't stated, but that (as said) namely
for __initdata objects, which put restrictions on where use of them
is valid, introducing them in one patch and adding uses only later is
difficult to review. Quite a bit more difficult than if such variables
got added only once needed (which "bloats" the affected patch by
just a handful of lines at most).
But anyway, I've got through it, and I'm not insisting on this needing
to change. I merely wanted to point out that while there are cases
where it's reasonable to add unused objects or functions to make
later stuff easier to review, I don't think this is such a case (at least
not as far as the variables here are concerned).
Jan
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next prev parent reply other threads:[~2016-03-22 16:16 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-15 15:34 [PATCH RFC v3 00/28] x86: Improvements to cpuid handling for guests Andrew Cooper
2016-03-15 15:34 ` [PATCH v3 01/28] xen/x86: Drop unused and non-useful feature definitions Andrew Cooper
2016-03-16 7:53 ` Konrad Rzeszutek Wilk
2016-03-16 9:49 ` Andrew Cooper
2016-03-22 14:06 ` Doug Goldstein
2016-03-22 14:38 ` Jan Beulich
2016-03-15 15:34 ` [PATCH v3 02/28] xen/x86: Rename features to be closer to the vendor definitions Andrew Cooper
2016-03-16 8:01 ` Konrad Rzeszutek Wilk
2016-03-17 19:46 ` Andrew Cooper
2016-03-15 15:34 ` [PATCH v3 03/28] xen/public: Export cpu featureset information in the public API Andrew Cooper
2016-03-16 8:32 ` Konrad Rzeszutek Wilk
2016-03-22 10:39 ` Andrew Cooper
2016-03-18 15:52 ` Jan Beulich
2016-03-15 15:35 ` [PATCH v3 04/28] xen/x86: Script to automatically process featureset information Andrew Cooper
2016-03-16 8:41 ` Konrad Rzeszutek Wilk
2016-03-15 15:35 ` [PATCH v3 05/28] xen/x86: Collect more cpuid feature leaves Andrew Cooper
2016-03-16 8:50 ` Konrad Rzeszutek Wilk
2016-03-15 15:35 ` [PATCH v3 06/28] xen/x86: Mask out unknown features from Xen's capabilities Andrew Cooper
2016-03-16 18:01 ` Konrad Rzeszutek Wilk
2016-03-15 15:35 ` [PATCH v3 07/28] xen/x86: Annotate special features Andrew Cooper
2016-03-16 18:04 ` Konrad Rzeszutek Wilk
2016-03-18 16:29 ` Jan Beulich
2016-03-15 15:35 ` [PATCH v3 08/28] xen/x86: Annotate VM applicability in featureset Andrew Cooper
2016-03-16 18:15 ` Konrad Rzeszutek Wilk
2016-03-18 16:57 ` Jan Beulich
2016-03-18 18:56 ` Andrew Cooper
2016-03-21 11:53 ` Jan Beulich
2016-03-21 13:39 ` Andrew Cooper
2016-03-15 15:35 ` [PATCH v3 09/28] xen/x86: Calculate maximum host and guest featuresets Andrew Cooper
2016-03-16 18:24 ` Konrad Rzeszutek Wilk
2016-03-18 17:09 ` Jan Beulich
2016-03-22 11:23 ` Andrew Cooper
2016-03-22 12:39 ` Jan Beulich
2016-03-22 14:37 ` Andrew Cooper
2016-03-22 14:52 ` Jan Beulich
2016-03-22 15:01 ` Andrew Cooper
2016-03-22 16:10 ` Jan Beulich
2016-03-15 15:35 ` [PATCH v3 10/28] xen/x86: Generate deep dependencies of features Andrew Cooper
2016-03-17 19:45 ` Konrad Rzeszutek Wilk
2016-03-17 20:14 ` Andrew Cooper
2016-03-17 20:32 ` Konrad Rzeszutek Wilk
2016-03-21 15:41 ` Jan Beulich
2016-03-15 15:35 ` [PATCH v3 11/28] xen/x86: Clear dependent features when clearing a cpu cap Andrew Cooper
2016-03-17 19:51 ` Konrad Rzeszutek Wilk
2016-03-17 19:56 ` Andrew Cooper
2016-03-28 15:02 ` Konrad Rzeszutek Wilk
2016-03-21 15:45 ` Jan Beulich
2016-03-15 15:35 ` [PATCH v3 12/28] xen/x86: Improve disabling of features which have dependencies Andrew Cooper
2016-03-15 15:35 ` [PATCH v3 13/28] xen/x86: Improvements to in-hypervisor cpuid sanity checks Andrew Cooper
2016-03-21 16:11 ` Jan Beulich
2016-03-22 15:30 ` Andrew Cooper
2016-03-15 15:35 ` [PATCH v3 14/28] x86/cpu: Move set_cpumask() calls into c_early_init() Andrew Cooper
2016-03-21 16:16 ` Jan Beulich
2016-03-15 15:35 ` [PATCH v3 15/28] x86/cpu: Sysctl and common infrastructure for levelling context switching Andrew Cooper
2016-03-15 17:35 ` Joao Martins
2016-03-15 19:29 ` Andrew Cooper
2016-03-15 19:34 ` Joao Martins
2016-03-21 16:23 ` Jan Beulich
2016-03-22 15:57 ` Andrew Cooper
2016-03-22 16:16 ` Jan Beulich [this message]
2016-03-15 15:35 ` [PATCH v3 16/28] x86/cpu: Rework AMD masking MSR setup Andrew Cooper
2016-03-21 16:51 ` Jan Beulich
2016-03-21 16:55 ` Andrew Cooper
2016-03-15 15:35 ` [PATCH v3 17/28] x86/cpu: Rework Intel masking/faulting setup Andrew Cooper
2016-03-21 16:44 ` Jan Beulich
2016-03-15 15:35 ` [PATCH v3 18/28] x86/cpu: Context switch cpuid masks and faulting state in context_switch() Andrew Cooper
2016-03-15 15:35 ` [PATCH v3 19/28] x86/pv: Provide custom cpumasks for PV domains Andrew Cooper
2016-03-21 16:53 ` Jan Beulich
2016-03-15 15:35 ` [PATCH v3 20/28] x86/domctl: Update PV domain cpumasks when setting cpuid policy Andrew Cooper
2016-03-21 17:06 ` Jan Beulich
2016-03-22 16:37 ` Andrew Cooper
2016-03-22 16:51 ` Jan Beulich
2016-03-15 15:35 ` [PATCH v3 21/28] xen+tools: Export maximum host and guest cpu featuresets via SYSCTL Andrew Cooper
2016-03-16 18:23 ` Wei Liu
2016-03-16 20:38 ` David Scott
2016-03-22 8:43 ` Jan Beulich
2016-03-22 20:39 ` Andrew Cooper
2016-03-15 15:35 ` [PATCH v3 22/28] tools/libxc: Modify bitmap operations to take void pointers Andrew Cooper
2016-03-16 15:24 ` Andrew Cooper
2016-03-17 12:17 ` Wei Liu
2016-03-15 15:35 ` [PATCH v3 23/28] tools/libxc: Use public/featureset.h for cpuid policy generation Andrew Cooper
2016-03-15 15:35 ` [PATCH v3 24/28] tools/libxc: Expose the automatically generated cpu featuremask information Andrew Cooper
2016-03-15 15:35 ` [PATCH v3 25/28] tools: Utility for dealing with featuresets Andrew Cooper
2016-03-16 18:23 ` Wei Liu
2016-03-15 15:35 ` [PATCH v3 26/28] tools/libxc: Wire a featureset through to cpuid policy logic Andrew Cooper
2016-03-15 15:35 ` [PATCH v3 27/28] tools/libxc: Use featuresets rather than guesswork Andrew Cooper
2016-03-15 15:35 ` [PATCH v3 28/28] tools/libxc: Calculate xstate cpuid leaf from guest information Andrew Cooper
2016-03-16 18:23 ` Wei Liu
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