Messages in this thread | | | Date | Fri, 26 Jan 2018 19:15:39 +0100 | From | Greg KH <> | Subject | Re: [PATCH v2 char-misc 1/1] Drivers: hv: vmbus: Implement Direct Mode for stimer0 |
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On Fri, Jan 26, 2018 at 05:34:28PM +0000, Michael Kelley (EOSG) wrote: > > -----Original Message----- > > From: Greg KH [mailto:gregkh@linuxfoundation.org] > > Sent: Thursday, January 25, 2018 2:00 AM > > To: Michael Kelley (EOSG) <Michael.H.Kelley@microsoft.com> > > Cc: linux-kernel@vger.kernel.org; devel@linuxdriverproject.org; olaf@aepfle.de; > > apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com; > > leann.ogasawara@canonical.com; marcelo.cerri@canonical.com; Stephen Hemminger > > <sthemmin@microsoft.com>; KY Srinivasan <kys@microsoft.com>; x86@kernel.org; > > jrp@pun.org > > Subject: Re: [PATCH v2 char-misc 1/1] Drivers: hv: vmbus: Implement Direct Mode for stimer0 > > > > On Mon, Jan 22, 2018 at 03:29:29PM -0700, mikelley@exchange.microsoft.com wrote: > > > +/* > > > + * If false, we're using the old mechanism for stimer0 interrupts > > > + * where it sends a VMbus message when it expires. The old > > > + * mechanism is used if Direct Mode is explicitly disabled > > > + * by the module parameter, or on older versions of Hyper-V > > > + * that don't support Direct Mode. While Hyper-V provides > > > + * four stimer's per CPU, Linux uses only stimer0. > > > + */ > > > +static bool direct_mode_enabled = true; > > > +module_param(direct_mode_enabled, bool, 0444); > > > +MODULE_PARM_DESC(direct_mode_enabled, > > > + "Set to N to disable stimer Direct Mode."); > > > > Ick ick ick. How is a distro or user supposed to know if/when to enable > > this and not to enable it? This isn't ok, can you please make this > > "automatic" to always do the right thing based on what it is running on? > > To be clear, this patch already does the "automatic" thing based on the > capabilities of the hypervisor. But it's often handy to be able to override > the automatic behavior without having to rebuild the kernel.
Then put the option somewhere else. sysfs, debugfs, somewhere else. Never a module parameter please, not for new code.
thanks,
greg k-h
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