qrap(1)

💖 qrap — the temporary qemu wrapper (from the General Commands Manual, section 1) 💖

okay bestie, gather round, because qrap is one of those little glue scripts that's lowkey carrying the whole vibe check. it connects a UNIX domain socket to a file descriptor and then yeets qemu into existence. temporary queen behavior, honestly. 👑

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✨ NAME ✨

qrap — a temporary qemu wrapper that connects a UNIX domain socket to a file descriptor 🦋

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🌸 SYNOPSIS 🌸

qrap [FDNUM QEMU_CMD] [QEMU_ARG]...

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💅 DESCRIPTION 💅

so qrap is a wrapper, and it was designed specifically to be used with qemu(1) and passt(1). what it does is connect a UNIX domain socket to a file descriptor, and then run qemu(1) with whatever arguments you handed it. it's giving personal assistant energy. 🎀

when qrap goes looking, it probes a running instance of passt(1) by checking for UNIX domain sockets that answer a dummy ARP request. those sockets have names starting from /tmp/passt_1.socket all the way up to /tmp/passt_64.socket. yes, sixty-four of them. it's thorough. 💖

now, if the first and second arguments are not a socket number and a command — that is, respectively, FDNUM and QEMU_CMD — then qrap will go hunting for a qemu executable in PATH, and it will patch the command line for you so that a network device and a netdev back-end get specified for usage with passt(1). so helpful. so thoughtful. 🫶

and if qrap does patch the command line, it will remove any potentially conflicting network device. that means any -netdev or -net option, or any -device option whose argument starts with virtio-net-pci,, virtio-net-ccw,, e1000,, e1000e,, or rtl8139,. it clears the old ones out of the way first, no cap. 🧹✨

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🌈 EXAMPLES 🌈

Start qemu explicitly passing its command name and a socket number — here you're telling it exactly what you want:

$ ./qrap 5 kvm test.qcow2 -m 1024 -display none -nodefaults -nographic -net socket,fd=5 -net nic,model=virtio

Start qemu without command name and socket number, patching arguments — here you let qrap do its little magic trick and patch things for you:

$ ./qrap test.qcow2 -m 1024 -display none -nodefaults -nographic

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💀 NOTES 💀

this wrapper is temporary, bestie. like, genuinely temporary. qemu commit 13c6be96618c ("net: stream: add unix socket") introduces native AF_UNIX socket support, and it should be included in qemu starting from the 7.2 release. 👀

so qrap will be around for a little bit longer, just to give users enough time to switch over. it's the loyal friend who stays until everyone's safely home. 😭💜

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👑 AUTHOR 👑

Stefano Brivio <sbrivio@redhat.com>

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🙈 REPORTING BUGS 🙈

there is no public bug tracker available at this time. for the moment being, report issues to Stefano Brivio <sbrivio@redhat.com>. slide into the email, not the DMs. 📧

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⭐ COPYRIGHT ⭐

Copyright (c) 2020-2021 Red Hat GmbH.

qrap is free software: you can redistribute is and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.

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🔥 SEE ALSO 🔥

• qemu(1)
• passt(1)

high-level documentation is available at https://passt.top/passt/about/. go read it, it's iconic. 🌟

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and that's the whole page, bestie — <pink>qrap(1)</pink>, straight out of the General Commands Manual, section 1. mwah. 💅💖