Here's a second attempt at MPX removal. The first one was not friendly to KVM live migration. We should probably apply the first two patches (at least) for 4.20+1. -- Unfortunately, GCC 9.1 is expected to be be released without support for MPX. This means that there was only a relatively small window where folks could have ever used MPX. It failed to gain wide adoption in the industry, and Linux was the only mainstream OS to ever support it widely. Support for the feature may also disappear on future processors. The benefits of keeping the feature in the tree is not worth the ongoing maintenance cost. This is an incremental, bisectable, set that removes MPX bit by bit. The only MPX code left in the kernel is the XSAVE state management which is currently still needed for guests that might use MPX. Keeping this code prevents breaking live migration between kernels which have MPX removed versus present. It was a fun run, but it's time for it to go. Adios, MPX! Cc: x86@xxxxxxxxxx Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: linux-mm@xxxxxxxxx
