On Fri, Jan 29, 2021 at 04:24:32PM -0800, Ben Widawsky wrote: > For drivers that moderate access to the underlying hardware it is > sometimes desirable to allow userspace to bypass restrictions. Once > userspace has done this, the driver can no longer guarantee the sanctity > of either the OS or the hardware. When in this state, it is helpful for > kernel developers to be made aware (via this taint flag) of this fact > for subsequent bug reports. > > Example usage: > - Hardware xyzzy accepts 2 commands, waldo and fred. > - The xyzzy driver provides an interface for using waldo, but not fred. > - quux is convinced they really need the fred command. > - xyzzy driver allows quux to frob hardware to initiate fred. Would it not be easier to _not_ frob the hardware for fred-operation? Aka not implement it or just disallow in the first place? > - kernel gets tainted. > - turns out fred command is borked, and scribbles over memory. > - developers laugh while closing quux's subsequent bug report. Yeah good luck with that theory in-the-field. The customer won't care about this and will demand a solution for doing fred-operation. Just easier to not do fred-operation in the first place,no?
