On 9/23/21 7:09 AM, Greg KH wrote: > And you forgot to mention that this is tied to one specific CPU type > only. Are syscalls allowed to be created that would only work on > obscure cpus like this one? Well, you have to start somewhere. For example, when memory protection keys went in, we added three syscalls: > 329 common pkey_mprotect sys_pkey_mprotect > 330 common pkey_alloc sys_pkey_alloc > 331 common pkey_free sys_pkey_free At the point that I started posting these, you couldn't even buy a system with this feature. For a while, there was only one Intel Xeon generation that had support. But, if you build it, they will come. Today, there is powerpc support and our friends at AMD added support to their processors. In addition, protection keys are found across Intel's entire CPU line: from big Xeons, down to the little Atoms you find in Chromebooks. I encourage everyone submitting new hardware features to include information about where their feature will show up to end users *and* to say how widely it will be available. I'd actually prefer if maintainers rejected patches that didn't have this information.
