867e762480
wrtspr() is a function to write an arbitrary value in a special register. It is used on 8xx to write to SPRN_NRI, SPRN_EID and SPRN_EIE. Writing any value to one of those will play with MSR EE and MSR RI regardless of that value. r0 is used many places in the generated code and using r0 for that creates an unnecessary dependency of this instruction with preceding ones using r0 in a few places in vmlinux. r2 is most likely the most stable register as it contains the pointer to 'current'. Using r2 instead of r0 avoids that unnecessary dependency. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/69f9968f4b592fefda55227f0f7430ea612cc950.1611299687.git.christophe.leroy@csgroup.eu
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.