[PATCH v2 00/12] x86: memcpy() / memset() (non-)ERMS flavors plus fallout

[Jan Beulich <jbeulich@xxxxxxxx>]

While the performance varies quite a bit on older (pre-ERMS) and newer
(ERMS) hardware, so far we've been going with just a single flavor of
these two functions, and oddly enough with ones not consistent with one
another. Using plain memcpy() / memset() on MMIO (video frame buffer)
is generally okay, but the ERMS variant of memcpy() turned out to
regress (boot) performance in a way easily visible to the human eye.
Hence as a prerequisite step this series switches the frame buffer
(and VGA) mapping to be write-combining independent of firmware
arrangements (of MTRRs in particular).

v2, besides addressing review feedback not addressed verbally, extends
things to
- driving gcc's inlining of __builtin_mem{cpy,set}(),
- page clearing and scrubbing.

01: x86: introduce ioremap_wc()
02: x86: re-work memset()
03: x86: re-work memcpy()
04: x86: control memset() and memcpy() inlining
05: x86: introduce "hot" and "cold" page clearing functions
06: page-alloc: make scrub_on_page() static
07: mm: allow page scrubbing routine(s) to be arch controlled
08: x86: move .text.kexec
09: video/vesa: unmap frame buffer when relinquishing console
10: video/vesa: drop "vesa-mtrr" command line option
12: video/vesa: adjust (not just) command line option handling

Side note: While strictly speaking the xen/drivers/video/ changes fall
under REST maintainership, with that code getting built for x86 only
I'm restricting Cc-s to x86 maintainers.

Jan