bincompat-memcached

[andreea110]

Add bincompat-memcached: run Memcached 1.6 in binary-compatibility mode, modeled on bincompat-c-hello, with elfloader-net as base.

The rootfs uses the system Memcached binary (apt install memcached) with its dynamic libraries, plus minimal /etc/passwd and /etc/group (needed
by -u root / getpwnam()).

Two options had to be enabled in the elfloader-net defconfigs:

• CONFIG_LIBPOSIX_FUTEX: without it pthread_create() fails with "Unsupported clone flags requested";
• CONFIG_LIBPOSIX_EVENTFD: Memcached needs eventfd2() for its worker threads.

Tested on QEMU/x86_64: set/get/stats work on 172.44.0.2:11211, plus automated tests in scripts/test/.
The Firecracker scripts are included but not fully verified: the test VM has no /dev/kvm, and my local CPU hits Unikraft/Firecracker issues
unrelated to this app.

[Copilot]

Pull request overview

Adds a new bincompat-memcached application that runs the system Memcached (1.6) as a Linux ELF under Unikraft’s binary-compatibility layer, using elfloader-net as the base and providing build/run/test automation for QEMU and Firecracker.

Changes:

• Enable futex + eventfd support in elfloader-net defconfigs to support Memcached threading requirements.
• Add bincompat-memcached rootfs build that bundles /usr/bin/memcached, required shared libraries, dynamic loader, and minimal passwd/group.
• Add build/run/test scripts (including a Firecracker config) plus companion documentation for running and testing.

Reviewed changes

Copilot reviewed 22 out of 22 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
elfloader-net/scripts/defconfig/qemu.x86_64	Enables additional POSIX features (futex/eventfd) needed by Memcached.
elfloader-net/scripts/defconfig/fc.x86_64	Enables additional POSIX features (futex/eventfd) needed by Memcached.
bincompat-memcached/setup.sh	Creates workdir/ layout and links required repos (modeled on other bincompat apps).
bincompat-memcached/scripts/test/wrapper.sh	Starts an instance and validates Memcached set/get behavior.
bincompat-memcached/scripts/test/README.md	Documents how to run the test scripts.
bincompat-memcached/scripts/test/common.sh	Shared test helpers for starting/stopping instances and probing services.
bincompat-memcached/scripts/test/all.sh	Builds and runs QEMU/FC test flows, capturing logs.
bincompat-memcached/scripts/test/.gitignore	Ignores test log output directory.
bincompat-memcached/scripts/run/qemu.x86_64	QEMU run wrapper configuring networking and boot args for memcached.
bincompat-memcached/scripts/run/fc.x86_64	Firecracker run wrapper configuring tap networking and VM config.
bincompat-memcached/scripts/README.md	Documents build/run/test script entrypoints.
bincompat-memcached/scripts/common.sh	Shared build helpers; builds the elfloader-net base for the chosen target.
bincompat-memcached/scripts/build/rootfs.x86_64	Builds the rootfs and packs it into initrd.cpio.
bincompat-memcached/scripts/build/qemu.x86_64	Builds rootfs + QEMU kernel.
bincompat-memcached/scripts/build/kernel.qemu.x86_64	Builds the elfloader-net base kernel for QEMU.
bincompat-memcached/scripts/build/kernel.fc.x86_64	Builds the elfloader-net base kernel for Firecracker.
bincompat-memcached/scripts/build/fc.x86_64	Builds rootfs + Firecracker kernel.
bincompat-memcached/rootfs/Makefile	Copies system memcached + shared libs and generates minimal /etc/passwd and /etc/group.
bincompat-memcached/rootfs/.gitignore	Ignores generated rootfs artifacts.
bincompat-memcached/README.md	Main app documentation for setup, build, run, and test.
bincompat-memcached/fc.x86_64.json	Firecracker VM configuration (boot args, initrd, networking).
bincompat-memcached/.gitignore	Ignores workdir/ and generated initrd.

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[Copilot]

Pull request overview

Copilot reviewed 22 out of 22 changed files in this pull request and generated 3 comments.

[razvand]

The rootfs/ directory must contain a Dockerfile and a Makefile that builds and extracts the required root filesystem. The Dockerfile should be actually the one from the examples/memcached1.6-base/ directory in the unikraft/catalog repository.

The Makefile would run the docker and extract the root filesystem. The Makefile here is a good starting point.

The current way to do a Makefile relies on local filesystem files that may or may not be present. The Dockerfile is the best way for that.