On Thu, Oct 25, 2018 at 10:19:54AM -0700, Florian Fainelli wrote: > On 10/24/18 7:10 PM, Andrew Lunn wrote: > > On Wed, Oct 24, 2018 at 05:09:05PM -0700, Florian Fainelli wrote: > >> perf on ARM requires CONFIG_KUSER_HELPERS to be turned on to allow some > >> independance with respect to the ARM CPU being used. Add a test which > >> tries to locate the [vectors] page, created when CONFIG_KUSER_HELPERS is > >> turned on to help asses the system's health. > > > > Hi Florian > > > > I've suffered the pain from missing CONFIG_KUSER_HELPERS. The > > segfaults give little clue as to what is going wrong,and gdb is not > > much use either. > > If you have a working backtrace, you can typically see the virtual > address being in 0xffff_xxxx which gives a bit of a clue, but yes, this > is not particularly helpful. > > > > > What i don't see here is any clue to CONFIG_KUSER_HELPERS. If the test > > fails, could you print a message suggesting CONFIG_KUSER_HELPERS on > > ARM? > > Sure, sounds reasonable, thanks for taking a look.
An alternative would be rather than adding this to user programs, to have the kernel detect it and print a warning itself. BTW, I note that the help text for CONFIG_KUSER_HELPERS needs to be updated. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
