# 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>>.

##### 37.6.1.2. Can caches snoop data from other caches?

Either they can snoop only control, or both control and data can be snooped.

The answer to this determines if some of the following design decisions make sense.

This is the central point in question at: https://electronics.stackexchange.com/questions/484830/why-is-a-flush-needed-in-the-msi-cache-coherency-protocol-when-moving-from-modif

If data snoops are not possible, then data must always to to DRAM first.