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Fenghua Yu
33823f4d63
MOVDIRI moves doubleword or quadword from register to memory through direct store which is implemented by using write combining (WC) for writing data directly into memory without caching the data. Programmable agents can handle streaming offload (e.g. high speed packet processing in network). Hardware implements a doorbell (tail pointer) register that is updated by software when adding new work-elements to the streaming offload work-queue. MOVDIRI can be used as the doorbell write which is a 4-byte or 8-byte uncachable write to MMIO. MOVDIRI has lower overhead than other ways to write the doorbell. Availability of the MOVDIRI instruction is indicated by the presence of the CPUID feature flag MOVDIRI(CPUID.0x07.0x0:ECX[bit 27]). Please check the latest Intel Architecture Instruction Set Extensions and Future Features Programming Reference for more details on the CPUID feature MOVDIRI flag. Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Ashok Raj <ashok.raj@intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi V Shankar <ravi.v.shankar@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1540418237-125817-2-git-send-email-fenghua.yu@intel.com Signed-off-by: Ingo Molnar <mingo@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.
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.