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1 g2boojum 1.1 GLEP: 22
2     Title: New "keyword" system to incorporate various userlands/kernels/archs
3 g2boojum 1.3 Version: $Revision: 1.2 $
4     Last-Modified: $Date: 2004/05/02 21:15:23 $
5 g2boojum 1.1 Author: Grant Goodyear <g2boojum@gentoo.org>
6 g2boojum 1.3 Status: Draft
7 g2boojum 1.1 Type: Standards Track
8     Content-Type: text/x-rst
9     Created: 6-Mar-2004
10 g2boojum 1.3 Post-History: 6-Mar-2004, 5-Jun-2004
11 g2boojum 1.1
12 g2boojum 1.2 Status
13     ======
15 g2boojum 1.3 After withdrawing this GLEP temporarily, a rewritten version has
16     now been resubmitted. This version no longer tries to prevent a
17     keyword explosion, but merely tries to make it manageable.
18 g2boojum 1.2
19 g2boojum 1.1 Credits
20     =======
22 g2boojum 1.3 This GLEP originated from the concerns that Daniel Robbins had with the
23     *x86obsd* keyword, and his desire to make the KEYWORDS variable more
24     "feature-rich". Drobbins' original idea was that we should allow compound
25 g2boojum 1.1 keywords such as gnu/x86, gnu/ppc, and macos/ppc (which would be explicit
26     versions of the more familiar x86, ppc, and macos keywords). Method noted
27 g2boojum 1.3 that userland/arch failed to capture the full range of possibilities (what
28     about a GNU userland on a BSD kernel+libc?), and the issue has languished due
29     to a lack of reasonable solutions. The original version of this GLEP
30     generated quite useful comments which hopefully have been addressed here to
31     make the GLEP much more reasonable.
32 g2boojum 1.1
33     Abstract
34     ========
36 g2boojum 1.3 As Gentoo branches out to support non-Linux and non-GNU systems (such as Hurd,
37     the \*BSDs, or even the soon-to-be-open-sourced Solaris), the potential for an
38     "explosion" of possible keywords becomes rather large, since each new
39     userland/kernel/arch/whatever combination will require a new keyword. This
40     GLEP proposes a simple extension to the current KEYWORDS variable that
41     encompasses the four parameters ARCH, USERLAND, KERNEL, and LIBC, but uses
42     sensible defaults to keep the new system manageable.
43 g2boojum 1.1
44     Motivation
45     ==========
47     Since the beginning, Gentoo Linux has been conceived as a "metadistribution"
48     that combines remarkable flexibility with sensible defaults and exceptional
49     maintainablilty. The goal of the Gentoo-Alt_ project has been to extend that
50     flexibility to include systems other than GNU/Linux. For example, the author
51 g2boojum 1.3 of this GLEP has been working to create a version_ of Gentoo that uses
52     OpenBSD_ as the underlying kernel, userland, and libc. OpenBSD_ supports a
53     variety of different architectures, so, in principle, we would need a new
54     *openbsd-arch* keyword for each supported architecture. In fact, the
55     situation is even more complicated, because the Gentoo-Alt_ project would
56     eventually like to support the option of "mixing-and-matching"
57     GNU/\*BSD/whatever userlands and libcs irrespective of the underlying kernel.
58     (Debian_, for example has a similar BSD project_, except that they have
59     replaced the BSD userland with a GNU userland.) The net result is that we
60     need keywords that can specify all possible permutations of arch,
61     userland, kernel and libc. A systematic nomenclature is needed.
62     Fortunately, the author is a Chemist. *Grin*
63 g2boojum 1.1
64     .. _Gentoo-Alt: http://www.gentoo.org/proj/en/gentoo-alt/index.xml
65     .. _OpenBSD: http://www.openbsd.com
66     .. _version: http://www.gentoo.org/proj/en/gentoo-alt/bsd/index.xml
67     .. _Debian: http://www.debian.org
68     .. _project: http://www.debian.org/ports/netbsd/
70     Specification
71     =============
73 g2boojum 1.3 Keyword Fragments
74     -----------------
75 g2boojum 1.1
76 g2boojum 1.3 Each keyword needs to specify, either explicitly or
77     implicitly, the following parameters: ARCH, USERLAND, LIBC, and KERNEL.
78 g2boojum 1.1
79     ARCH:
80     x86, amd64, cobalt, mips64, arm, hppa, ia64, ppc64, sparc
81     USERLAND:
82     gnu, bsd
83     LIBC:
84     glibc, openbsd, freebsd, netbsd, macosx
85     KERNEL:
86     linux, selinux, openbsd, freebsd, netbsd, macosx
88     (The above examples are not meant to be complete. Hurd, for example
89     is not included because I know very little about Hurd.)
90 g2boojum 1.3
91     A fully-specified keyword would look like
92     "ARCH-KERNEL-USERLAND-LIBC", so, for example,
93     "ppc-fbsd-gnu-glibc" would indicate a Gentoo system corresponding to
94     a ppc architecture running the FreeBSD kernel with a GNU userland and glibc
95     as the system C library.
96 g2boojum 1.1
97     Reasonable Defaults
98     -------------------
100 g2boojum 1.3 To keep this system manageable (and both to reduce typing and maintain
101     backwards compatibility), we need sensible defaults. For backwards
102     compatibility, the Gentoo default is a Linux kernel with a GNU userland
103     and glibc C library. Thus, the current crop of ARCH-based keywords
104     (x86, ppc, etcetera) require no change whatsoever. For the \*BSD-based
105     systems the default USERLAND and LIBC would be those normally associated
106     with the corresponding KERNEL, so "x86-obsd" describes an x86 system
107     with an OpenBSD kernel, a BSD userland, and the OpenBSD C library. If
108     either USERLAND or LIBC is specified, and thus not the default, then the
109     entire four-parameter string must be used.
112     Ebuild Keyword Database?
113     ------------------------
115     One issue that has been raised is that adding a large number of keywords
116     to ebuilds is likely to become cumbersome over the long run. (One could
117     imagine that for a simple `econf && emake && einstall` ebuild that the
118     list of keywords could grow to be the lengthiest part of the ebuild.)
119     Instead, perhaps it would make more sense to move each ebuild's keywords
120     out of the ebuild proper into a separate, perhaps online, database.
121     Nothing in this GLEP would be incompatible with such an approach, so
122     any further discussion will be deferred to a possible future GLEP on
123     that topic.
125 g2boojum 1.1
126     Profiles
127     --------
129 g2boojum 1.3 Along with an explosion of keywords comes a concomitant explosion of potential
130     profiles. Just as in the current system, the profile name would be
131     "DESCRIPTION-KEYWORD-VERSION" (such as "default-s390-2004.1"). One drawback
132     to having a large number of profiles is that maintainance becomes a
133     significant problem. In fact, one could reasonably argue that the current
134     number of profiles is already too many to be easily maintained. One proposal
135     that has been raised to simplify matters is the idea of stackable, or
136     cascading, profiles, so that only differences between profiles would have to
137     be maintained.
139 g2boojum 1.1
140     Rationale
141     =========
143     The proposed new "keywording" system is far from elegant, which is
144     a substantial drawback. On the other hand, it is simple, it requires
145 g2boojum 1.3 relatively minor changes, and the changes can be implemented
146 g2boojum 1.1 gradually over time.
148 g2boojum 1.3
149 g2boojum 1.1 Implementation
150     ==============
152 g2boojum 1.3 Since the new keyword system is backwards-compatible with the current
153     system, "implementation" just means adding new keywords to ebuilds
154     as new systems are supported.
155 g2boojum 1.1
157     Backwards Compatibility
158     =======================
160     Backwards compatibility has already been addressed in some detail,
161     with the stated goal being a system that would leave all current
162 g2boojum 1.3 ebuilds working exactly as they are now.
163 g2boojum 1.1
165     Copyright
166     =========
168 g2boojum 1.3 This document has been placed in the public domain.

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