On 19/12/2020 20:09, Gordon Messmer wrote: > On 12/19/20 1:13 AM, Peter Georg wrote: >> However I disagree on one point: You mention CentOS Stream can cover >> "95% (or so)" of the current users. As long as 3rd party drivers are >> not working with CentOS Stream the number will be lower. > > > Do you have a reason to think that > 5% of users need 3rd party drivers? > > >> In my opinion, the only way to guarantee compatibility is by 100% >> kernel ABI compatibility. > > Stream is going to continue to get the same kernel that RHEL gets, > it's just going to get updates earlier. No, it's not, That's the point. It's going to have the unstable kernel from the NEXT point release so it will not be the same kernel as the current RHEL point release. Case in point, RHEL 8.3 has 4.18.0-240 series kernels, Stream had changed to a 4.18.0-257 kernel within 2 or 3 days of CentOS 8.3 being released. > In the past, users with binary 3rd party drivers would need to wait a > while after a point release before they could update their kernel. In > CentOS Stream, they'll have to wait a while after a kernel package > update before they can update their kernel. And that change happened on a predictable, approximately 6 month interval. And required the third party drivers to be rebuild once per point release and usually, by the time the CentOS build was done, those drivers were already rebuilt and already available since they had been done for the preceding RHEL point release. So we're going from a once every 6 months rebuild to a once every time the RHEL kernel developers feel like changing. Those changes were abstracted from the CentOS and RHEL kernels by the fact that KABI changes only happened (intentionally!) at point releases. Now that will change whenever someone in the kernel development team commits a breaking change. So we're going from a rebuild the drivers every 6 months to rebuild the drivers whenever RH feel like breaking it. That could be once a month or once a week or every time the kernel is updated or even once every 6 months like stable RHEL (though the chances of that are slim IMO). And since RHEL will still be using the old kernel series, that means that the third party yum repos have to invent a new way to cater for both RHEL and Stream since they will be different. Trevor