Messages in this thread |  | | Date | Wed, 6 Feb 2013 14:16:55 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] x86, apic: Check fadt x2apic phys in x2apic_phys_probe() |
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* Yinghai Lu <yinghai@kernel.org> wrote:
> On Tue, Feb 5, 2013 at 4:24 AM, Ingo Molnar <mingo@kernel.org> wrote: > > > > * Yinghai Lu <yinghai@kernel.org> wrote: > > > >> From: Stoney Wang <song-bo.wang@hp.com> > >> > >> When HP ProLiant DL980 G7 Server boot without x2apic_phys, there will be > >> intermittent lost interrupts and could result in a hang or data loss. > > > > What does 'boot without x2apic_phys' mean? > > > > Does it mean x2apic_phys=0 boot command line? Or, because > > x2apic_phys is off by default, does it simply mean that if it's > > booted with a default kernel, without any workaround specified > > on the boot command line? > > means that user does not append "x2apic_phys" in boot command line.
The user does not append a whole lot of other behavior-modification command line options either! There's no apic=0 line either. Nor smp=0.
Adding this essentially irrelevant piece of information to the *FIRST*, most important sentence of the changelog is thus not just confusing but utterly misleading. Communications 101.
Instead it should say something like:
When a HP ProLiant DL980 G7 Server boots a regular kernel, there will be intermittent lost interrupts which could result in a hang or (in extreme cases) data loss.
The reason is that this system only supports x2apic physical mode, while the kernel boots with a logical-cluster default setting.
This bug can be worked around by specifying the x2apic_phys=1 boot option, but we want to handle this sytem without requiring manual workarounds.
Right? Writing a clean changelog is like writing clean code - you have to learn it if you want to contribute to the kernel smoothly. Think of it as an engineering task: the other required half of modifying kernel code.
Thanks,
Ingo
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