b060b7d0c1
__switch_to() is final step of context switch, swapping kernel modes stack (and callee regs) of outgoing task with next task. It is also the starting point of stack unwinging of a sleeping task and captures SP, FP, BLINK and the corresponding dwarf info. Back when dinosaurs still roamed around, ARC gas didn't support CFI pseudo ops and gcc was responsible for generating dwarf info. Thus it had to be written in "C" with inline asm to do the hand crafting of stack. The function prologue (and crucial saving of blink etc) was still gcc generated but not visible in code. Likewise dwarf info was missing. Now with modern tools, we can make things more obvious by writing the code in asm and adding approproate dwarf cfi pseudo ops. This is mostly non functional change, except for slight chnages to asm - ARCompact doesn't support MOV_S fp, sp, so we use MOV Signed-off-by: Vineet Gupta <vgupta@kernel.org>
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.