Arch Linux Drops GCC 9 From Testing Due To BCache Corruption Bug
If using the GCC 9 compiler to build the Linux kernel, this latest version of the GNU compiler is yielding faulty code that could lead to file-system corruption around BCache. This is the BCache corruption issue we pointed out earlier this month around Linux 5.0+ and GCC 9. But it's not to be confused with the other LVM/DM/SSD FSTRIM corruption bug talked about last week.
This kernel corruption bug when built by GCC9 appears to only come out if BCache is in use as a block cache in writeback or writethrough caching modes, if you aren't using the feature there doesn't appear to be any known pressing issues with using the new compiler to assemble your kernel.
This code generation bug of GCC9 is still being sorted out upstream so for the time being Arch Linux has dropped the compiler from its testing area so users don't inadvertently use it to build a problematic kernel. More details for Arch users on their mailing list.