6c43eaffe4
At this time xentools413 will only build on a very recent -current (as of an hour ago or do - with /usr/include/xen/xenio.h 1.12 or newer) Xen is a hypervisor which supports running multiple guest operating systems on a single machine. Guest OSes (also called "domains") can be either paravirtualised (i.e. make hypercalls in order to access hardware), run in HVM (Hardware Virtualisation Mode) where they will be presented with virtual devices, or a combination where they use hypercalls to access hardware but manage memory themselves. At boot, the xen kernel is loaded along with the guest kernel for the first domain (called domain0). domain0 has privileges to access the physical hardware (PCI and ISA devices), administrate other domains and provide virtual devices (disks and network) to other domains.
72 lines
2.2 KiB
Bash
72 lines
2.2 KiB
Bash
#!/bin/sh
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#
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# Copyright (c) 2016, Christoph Badura. All rights reserved.
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#
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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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# 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 the
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# documentation and/or other materials provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS
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# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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# DISCLAIMED. IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT,
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# INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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# SUCH DAMAGE.
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#
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LOCK_BASEDIR="$XEN_LOCK_DIR/xen-hotplug"
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_lockfd=9
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_have_lock=0 # lock not taken yet.
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SHLOCK="shlock ${_shlock_debug-}"
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_lock_set_vars() {
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_lockfile="$LOCK_BASEDIR/$1.lock"
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_lockfifo="$LOCK_BASEDIR/$1.fifo"
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}
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_lock_init() {
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mkdir -p "$LOCK_BASEDIR" 2>/dev/null || true
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mkfifo $_lockfifo 2>/dev/null || true
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}
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#
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# use a named pipe as condition variable
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# opening for read-only blocks when there's no writer.
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# opening for read-write never blocks but unblocks any waiting readers.
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#
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_lock_wait_cv() {
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eval "exec $_lockfd< $_lockfifo ; exec $_lockfd<&-"
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}
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_lock_signal_cv() {
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eval "exec $_lockfd<> $_lockfifo ; exec $_lockfd<&-"
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}
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claim_lock() {
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_lock_set_vars $1
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_lock_init
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until $SHLOCK -f $_lockfile -p $$; do
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_lock_wait_cv
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done
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_have_lock=1
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# be sure to release the lock when the shell exits
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trap "release_lock $1" 0 1 2 15
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}
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release_lock() {
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_lock_set_vars $1
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[ "$_have_lock" != 0 -a -f $_lockfile ] && rm $_lockfile
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_have_lock=0
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_lock_signal_cv;
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}
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