forked from Minki/linux
mainlining shenanigans
ae1d557d8f
A SoC variant of Geode GX1, notably NSC branded SC1100, seems to report an inverted Device ID in its DIR0 configuration register, specifically 0xb instead of the expected 0x4. Catch this presumably quirky version so it's properly recognized as GX1 and has its cache switched to write-back mode, which provides a significant performance boost in most workloads. SC1100's datasheet "Geode™ SC1100 Information Appliance On a Chip", states in section 1.1.7.1 "Device ID" that device identification values are specified in SC1100's device errata. These, however, seem to not have been publicly released. Wading through a number of boot logs and /proc/cpuinfo dumps found on pastebin and blogs, this patch should mostly be relevant for a number of now admittedly aging Soekris NET4801 and PC Engines WRAP devices, the latter being the platform this issue was discovered on. Performance impact was verified using "openssl speed", with write-back caching scaling throughput between -3% and +41%. Signed-off-by: Christian Sünkenberg <christian.suenkenberg@student.kit.edu> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1496596719.26725.14.camel@student.kit.edu Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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arch | ||
block | ||
certs | ||
crypto | ||
Documentation | ||
drivers | ||
firmware | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.cocciconfig | ||
.get_maintainer.ignore | ||
.gitattributes | ||
.gitignore | ||
.mailmap | ||
COPYING | ||
CREDITS | ||
Kbuild | ||
Kconfig | ||
MAINTAINERS | ||
Makefile | ||
README |
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.