On 07/28/2015 10:02 AM, David Drysdale wrote: > On Tue, Jul 28, 2015 at 3:19 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: >> On Tue, Jul 28, 2015 at 07:59:16AM -0600, Shuah Khan wrote: >>> On 07/28/2015 05:41 AM, David Drysdale wrote: >>>> Given that I've gotten some of the details wrong in the past (and I've >>>> seen others do likewise), I thought it might be helpful to collate the >>>> best practices for adding a new system call to the kernel. >>>> >>>> Apologies for the wide circulation -- I've tried to include folk who've >>>> recently added or proposed a system call, as they're most likely to >>>> have opinions on: >>>> - whether this a useful addition to Documentation/ >>>> - whether the details of the advice are correct and complete. >>>> >>>> Shuah, is there anything more that should be added for the Testing >>>> section in particular? >>>> >>> >>> David, >>> >>> Looks good. You could add a one liner on in some cases, it might be >>> necessary to install headers before test compiles. Other than that, >>> the information looks good. >> >> For perf we still use the syscall() wrapper and we have hardcoded >> (fallback) syscall numbers in there in case they've not yet reached >> unistd.h. >> >> People update their kernels far more often than their userspace headers. > > How about: > > diff --git a/Documentation/adding-syscalls.txt > b/Documentation/adding-syscalls.txt > index 5f52edda8951..b274c3d01edb 100644 > --- a/Documentation/adding-syscalls.txt > +++ b/Documentation/adding-syscalls.txt > @@ -389,6 +389,11 @@ reviewers with a demonstration of how user space > programs will use the system > call. A good way to combine these aims is to include a simple self-test > program in a new directory under tools/testing/selftests/. > > +For a new system call, there will obviously be no libc wrapper function and so > +the test will need to invoke it using syscall(); also, if the system call > +involves a new userspace-visible structure, the corresponding header will need > +to be installed to compile the test. > + This looks good. thanks, -- Shuah -- Shuah Khan Sr. Linux Kernel Developer Open Source Innovation Group Samsung Research America (Silicon Valley) shuahkh@xxxxxxxxxxxxxxx | (970) 217-8978 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
