Messages in this thread | | | Date | Wed, 20 Jun 2018 00:34:32 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [RFC PATCH 7/8] x86/lib_user_wait.h: Add APIs for user wait instructions |
| |
On Tue, 19 Jun 2018, Fenghua Yu wrote: > On Tue, Jun 19, 2018 at 11:12:05AM +0200, Thomas Gleixner wrote: > > On Fri, 15 Jun 2018, Fenghua Yu wrote: > > > > > A few new user wait instructions UMONITOR, UMWAIT, and TPAUSE are > > > published in the latest Intel Instruction Set Extensions document. > > > > > > Define the APIs for user or kernel to use the instructions. > > > > You're not defining APIs. You're adding a pile of misdesigned helper > > functions which again add static storage per compilation unit and CPUID > > fiddling. > > > > If you want to add proper APIs then add the stuff to the VDSO and be done > > with it. > > The user wait instructions are mainly called by user apps; but they can > be used in kernel as well. > > I'm planning to provide five APIs to user: > 1. If user wait feature is supported > 2. nsec to tsc translation > 3. umonitor function that exectes UMONITOR instruction > 4. umwait function that executes UMWAIT instruction > 5. tpause function that executes TPAUSE instruction > > Seems 1-2 can be implemented in VDSO. But should I implement 3-5 in > VDSO/kernel as well?
If you want a real API, then yes. If not, then an UAPI header is definitely not the place for this.
Thanks
tglx
| |