Messages in this thread | | | Subject | Re: [PATCH v5 2/4] mm: Provide kernel parameter to allow disabling page init poisoning | From | Alexander Duyck <> | Date | Tue, 25 Sep 2018 13:38:43 -0700 |
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On 9/25/2018 1:26 PM, Dave Hansen wrote: > On 09/25/2018 01:20 PM, Alexander Duyck wrote: >> + vm_debug[=options] [KNL] Available with CONFIG_DEBUG_VM=y. >> + May slow down system boot speed, especially when >> + enabled on systems with a large amount of memory. >> + All options are enabled by default, and this >> + interface is meant to allow for selectively >> + enabling or disabling specific virtual memory >> + debugging features. >> + >> + Available options are: >> + P Enable page structure init time poisoning >> + - Disable all of the above options > > Can we have vm_debug=off for turning things off, please? That seems to > be pretty standard.
No. The simple reason for that is that you had requested this work like the slub_debug. If we are going to do that then each individual letter represents a feature. That is why the "-" represents off. We cannot have letters represent flags, and letters put together into words. For example slub_debug=OFF would turn on sanity checks and turn off debugging for caches that would have causes higher minimum slab orders.
Either I can do this as a single parameter that supports on/off semantics, or I can support it as a slub_debug type parameter that does flags based on the input options. I would rather not muddy things by trying to do both.
> Also, we need to document the defaults. I think the default is "all > debug options are enabled", but it would be nice to document that.
In the description I call out "All options are enabled by default, and this interface is meant to allow for selectively enabling or disabling".
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