>>>>> "James" == James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> writes: James> On Wed, 2018-04-25 at 19:00 -0400, Mikulas Patocka wrote: >> >> On Wed, 25 Apr 2018, James Bottomley wrote: >> >> > > > Do we really need the new config option? This could just be >> > > > manually tunable via fault injection IIUC. >> > > >> > > We do, because we want to enable it in RHEL and Fedora debugging >> > > kernels, so that it will be tested by the users. >> > > >> > > The users won't use some extra magic kernel options or debugfs >> files. >> > >> > If it can be enabled via a tunable, then the distro can turn it on >> > without the user having to do anything. If you want to present the >> > user with a different boot option, you can (just have the tunable >> set >> > on the command line), but being tunable driven means that you don't >> > have to choose that option, you could automatically enable it under >> a >> > range of circumstances. I think most sane distributions would want >> > that flexibility. >> > >> > Kconfig proliferation, conversely, is a bit of a nightmare from >> both >> > the user and the tester's point of view, so we're trying to avoid >> it >> > unless absolutely necessary. >> > >> > James >> >> BTW. even developers who compile their own kernel should have this >> enabled by a CONFIG option - because if the developer sees the option >> when browsing through menuconfig, he may enable it. If he doesn't see >> the option, he won't even know that such an option exists. James> I may be an atypical developer but I'd rather have a root canal James> than browse through menuconfig options. The way to get people James> to learn about new debugging options is to blog about it (or James> write an lwn.net article) which google will find the next time James> I ask it how I debug XXX. Google (probably as a service to James> humanity) rarely turns up Kconfig options in response to a James> query. I agree with James here. Looking at the SLAB vs SLUB Kconfig entries tells me *nothing* about why I should pick one or the other, as an example. John
