Michael Ellerman
2b84a2e844
commit993e3d96fdupstream. The device tree CPU features binding includes FSCR bit numbers which Linux is instructed to set by firmware. Whether that's a good idea or not, in the case of the DSCR the Linux implementation has a hard requirement that the FSCR_DSCR bit not be set by default. We use it to track when a process reads/writes to DSCR, so it must be clear to begin with. So if firmware tells us to set FSCR_DSCR we must ignore it. Currently this does not cause a bug in our DSCR handling because the value of FSCR that the device tree CPU features code establishes is only used by swapper. All other tasks use the value hard coded in init_task.thread.fscr. However we'd like to fix that in a future commit, at which point this will become necessary. Fixes:5a61ef74f2("powerpc/64s: Support new device tree binding for discovering CPU features") Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200527145843.2761782-2-mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.