Hi T.J., > *While I am not commenting as to their ultimate aims, which OVERALL are actually quite admirable and agnostic, it is still less than desirable that a key technology: KMS IS part of the* *> initial implementation, which in turn becomes the "reference implementation" for all practical purposes. KMS as a software is Linux specific. While there are equivalents out there, they* *> are certainly less developed. When I criticize Wayland, it is over concern that Linux-isms have worked their way into the final version of the stack, making it less portable to systems not* *> using Linux KMS. I think you can agree that that concern is not entirely unjustified, given that a number of supposedly platform agnostic software projects have Linux peculiarities in * *> their code that make them difficult to port to other UNIXes. *
I don't think I follow. KMS is a generic OS design concept, in the same way that "memory paging" and "preemptive multi-tasking" are generic OS design concepts. Each OS that does video mode setting in the kernel has its own API and implementation for doing so. Maybe one day POSIX will specify a consistent API that OS developers could implement, but that day is a long way off. The BSDs are on-board with not only adding KMS, but also GEM. Both are much simpler to implement and reason about than trying to get DRM and user mode-setting to cooperate with X while getting decent performance and good security. Here's a good perspective from the OpenBSD journal in 2008 on the subject, for example: http://undeadly.org/cgi?action=article&sid=20081029164221 -Jude On Mon, Mar 23, 2015 at 6:36 PM, T.J. Duchene <[email protected]> wrote: > > > > > *From:* Jude Nelson [mailto:[email protected]] > *Sent:* Monday, March 23, 2015 3:50 PM > *To:* T.J. Duchene > *Cc:* [email protected] > *Subject:* Re: [Dng] FW: Devuan commitments - will trade-off be applied? > > > > Technically, Wayland is the protocol definition, not the implementation > (i.e. think X11 vs X.org). Weston is the reference implementation. > > > > *[T.J. ] Good point. I was using the term Wayland more or less > generically. Yes, I know, but thank you for the correction. Hopefully, > it will be less confusing. * > > > > While it is true that most of the Wayland/Weston developers are also X.org > developers (and most come from Linux), they are making all the right moves > to avoid lock-in to Linux or a particular Wayland implementation. For > example, while there are multiple Wayland implementations (i.e. a Wayland > window manager or widget toolkit is effectively a Wayland protocol > implementation), inconsistencies between an implementation and the > specification are treated as bugs in the implementation. As another > example, Wayland avoids relying on FreeDesktop technologies like dbus and > systemd. > > > > *[T.J. ] Also correct. * > > You may be interested to know that the Wayland protocol is not tied to a > particular rendering technology or paradigm. To use the OSI analogy, > Wayland lives in the presentation layer--it's concerned with helping > applications identify and interact with the host's output devices, input > devices, and pixel memory buffers (on both an individual level and by > groupings). The protocol itself is not concerned with users, sessions, or > GPU infrastructure, nor is it concerned with widget sets, windowing, > decorations, etc. > > > *[T.J. ] Yes, I know.* > > > > > > > *While I am not commenting as to their ultimate aims, which OVERALL are > actually quite admirable and agnostic, it is still less than desirable that > a key technology: KMS IS part of the initial implementation, which in turn > becomes the "reference implementation" for all practical purposes. KMS as > a software is Linux specific. While there are equivalents out there, they > are certainly less developed. When I criticize Wayland, it is over concern > that Linux-isms have worked their way into the final version of the stack, > making it less portable to systems not using Linux KMS. I think you can > agree that that concern is not entirely unjustified, given that a number of > supposedly platform agnostic software projects have Linux peculiarities in > their code that make them difficult to port to other UNIXes. I freely > admit that until we see the final version of Wayland, it is hard to judge > if it is merely overcaution.*T.J. >
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