This repo contains a minimal config for the Linux kernel (6.7.3) that only enables:

• VirtIO devices
• Ext4
• IP stack (with autoconfig)

There's a no-smp and an smp config. no-smp boots a bit faster but limits you to 1 CPU.

On my laptop, no-smp boots to PID1 in 10ms.

There are also 2 patches:

• A patch for the kernel (linux_sleep.patch) to disable a 10-20ms wait on IP autoconfig
• A patch for firecracker (firecracker.patch) to pass the MAP_HUGETLB flag to mmap for fewer page faults (3-4ms of boot time was spent on page fault handling).