x86: add MIRROR_PAYLOAD_TO_RAM_BEFORE_LOADING option

Boot speeds can be sped up by mirroring the payload into
main memory before doing the actual loading. Systems that
would benefit from this are typically Intel ones whose SPI
are memory mapped. Without the SPI being cached all accesses
to the payload in SPI while being loaded result in uncacheable
accesses. Instead take advantage of the on-board SPI controller
which has an internal cache and prefetcher by copying 64-byte
cachelines using 32-bit word copies.

Change-Id: I4aac856b1b5130fa2d68a6c45a96cfeead472a52
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/5305
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/cpu/x86/Kconfig b/src/cpu/x86/Kconfig
index 19fa246fe2..b5bb7e62c2 100644
--- a/src/cpu/x86/Kconfig
+++ b/src/cpu/x86/Kconfig
@@ -121,3 +121,12 @@ config BACKUP_DEFAULT_SMM_REGION
 	help
 	 The cpu support will select this option if the default SMM region
 	 needs to be backed up for suspend/resume purposes.
+
+config MIRROR_PAYLOAD_TO_RAM_BEFORE_LOADING
+	def_bool n
+	help
+	  On certain platforms a boot speed gain can be realized if mirroring
+	  the payload data stored in non-volatile storage. On x86 systems the
+	  payload would typically live in a memory-mapped SPI part. Copying
+	  the SPI contents to ram before performing the load can speed up
+	  the boot process.