2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
105 lines
3.3 KiB
Groff
105 lines
3.3 KiB
Groff
.\" $NetBSD: cdb.5,v 1.3 2010/04/27 14:26:52 jruoho Exp $
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.\"
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.\" Copyright (c) 2010 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Joerg Sonnenberger.
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\"
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in
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.\" the documentation and/or other materials provided with the
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.\" distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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.\" FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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.\" COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
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.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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.\" OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.Dd April 27, 2010
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.Dt CDB 5
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.Os
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.Sh NAME
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.Nm cdb
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.Nd format of the constant database
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.Sh DESCRIPTION
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The
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.Nm
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database format provides a space-efficient (key,value) database.
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The format doesn't allow updates in any convenient form.
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The file overhead is around 5 bytes per key and 5 bytes per entry.
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Keys are not stored and it is the responsibility of the caller
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to validate matches.
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The index structure is based on a minimal perfect hash table, so exactly
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one entry has to be checked for a match.
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.Ss General Format
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The header record of a
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.Nm
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database consists of the following:
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.Bd -literal -offset indent
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struct header_cdb {
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uint8_t magic[7];
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uint8_t version;
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uint8_t description[16];
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uint32_t data_size;
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uint32_t entries;
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uint32_t entries_index;
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uint32_t seed;
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};
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.Ed
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.Pp
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All fields are in Little Endian byte order.
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.Pp
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This is followed by a description of the hash function of
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.Va entries_index
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records.
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The size of each index entry is the logarithm of
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.Va entries
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to base 256, rounded up.
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.Pp
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The index records are followed by the start offsets of the entries,
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followed by
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.Va data_size .
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The offsets are relative to the end of the offset record table and are
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monotically increasing.
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The size of each offset record is the logarithm of
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.Va data_size
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to base 256, rounded up.
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.Pp
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The offset table is followed by the entries in order.
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No separation or padding is added.
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.Ss Limitations
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The
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.Nm
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file format is by design intended for a database that can be
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mapped into memory.
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The hard limit for the number of entries and keys is 3435973836.
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The total size of all values must be smaller than 4GiB.
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.Sh SEE ALSO
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.Xr cdbr 3 ,
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.Xr cdbw 3
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.Sh HISTORY
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Support for the
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.Nm cdb
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format first appeared in
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.Nx 6.0 .
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.Sh AUTHORS
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The
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.Nm cdbr
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and
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.Nm cdbw
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functions have been written by
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.An Joerg Sonnenberger Aq joerg@NetBSD.org .
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