# Linux Kernel Module Cheat
The perfect emulation setup to study and develop the <<linux-kernel>> v5.9.2, kernel modules, <<qemu-buildroot-setup,QEMU>>, <<gem5-buildroot-setup,gem5>> and x86_64, ARMv7 and ARMv8 <<userland-assembly,userland>> and <<baremetal-setup,baremetal>> assembly, <<c,ANSI C>>, <<cpp,C++>> and <<posix,POSIX>>. <<gdb>> and <<kgdb>> just work. Powered by <<about-the-qemu-buildroot-setup,Buildroot>> and <<about-the-baremetal-setup,crosstool-NG>>. Highly automated. Thoroughly documented. Automated <<test-this-repo,tests>>.

###### 17.12.2.1.1. QEMU xp

The `xp` QEMU monitor command reads memory at a given physical address.

First launch `linux/virt_to_phys_user.out` as described at Userland physical address experiments.

On a second terminal, use QEMU to read the physical address:

    ./qemu-monitor 'xp 0x7c7b800'

Output:

    0000000007c7b800: 0x12345678

Yes!!! We read the correct value from the physical address.

We could not find however to write to memory from the QEMU monitor, boring.