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whiterose

Linux UniKernel

Clone

git clone https://git.mobley.ne02ptzero.me/~louis/whiterose

Configuration

One must toggle the UKL mode with the UKL_LINUX configuration token. You can activate it with make defconfig or by hand with make menuconfig

Compilation

Compilation of the UKL program is pretty simple:

export ukl-obj-m := main.o

all:
    make -C ../whiterose/ UKL=$(PWD) bzImage

This is a basic Makefile that adds the main.c file in the kernel. Here, whiterose is my kernel tree.

Running

Once the kernel is compiled, one can launch it via usual tools. Here's my command line:

qemu-system-x86_64 -enable-kvm -m 1G -s -kernel ../whiterose/arch/x86/boot/bzImage -append "console=ttyS0 root=/dev/sda ukl quiet" -nographic -hda qemu-image.img

The important bit is passing ukl to the kernel command line, otherwise the UKL will not be runned.

Example program

You can find some working examples here: https://github.com/jzck/unikernel-demo

#include <unistd.h>
#include <fcntl.h>

#ifndef USERSPACE
# define main ukl_main
#endif

int main(void) {
    char        buf[256] = { 0 };
    int         fd = open("/etc/passwd", O_RDONLY);
    ssize_t     ret;

    if (fd == -1)
        return 1;

    while ((ret = read(fd, buf, sizeof(buf))))
    {
        buf[ret] = 0;
        write(1, buf, ret);
    }

    close(fd);

    return 0;
}

One can either compile this program in the UKL or in userspace with:

gcc main.c -DUSERSPACE -o out