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author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-09 22:34:26 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-09 22:34:26 +0300 |
commit | e9a83bd2322035ed9d7dcf35753d3f984d76c6a5 (patch) | |
tree | 66dc466ff9aec0f9bb7f39cba50a47eab6585559 /Documentation/mic/mic_overview.rst | |
parent | 7011b7e1b702cc76f9e969b41d9a95969f2aecaa (diff) | |
parent | 454f96f2b738374da4b0a703b1e2e7aed82c4486 (diff) | |
download | linux-e9a83bd2322035ed9d7dcf35753d3f984d76c6a5.tar.xz |
Merge tag 'docs-5.3' of git://git.lwn.net/linux
Pull Documentation updates from Jonathan Corbet:
"It's been a relatively busy cycle for docs:
- A fair pile of RST conversions, many from Mauro. These create more
than the usual number of simple but annoying merge conflicts with
other trees, unfortunately. He has a lot more of these waiting on
the wings that, I think, will go to you directly later on.
- A new document on how to use merges and rebases in kernel repos,
and one on Spectre vulnerabilities.
- Various improvements to the build system, including automatic
markup of function() references because some people, for reasons I
will never understand, were of the opinion that
:c:func:``function()`` is unattractive and not fun to type.
- We now recommend using sphinx 1.7, but still support back to 1.4.
- Lots of smaller improvements, warning fixes, typo fixes, etc"
* tag 'docs-5.3' of git://git.lwn.net/linux: (129 commits)
docs: automarkup.py: ignore exceptions when seeking for xrefs
docs: Move binderfs to admin-guide
Disable Sphinx SmartyPants in HTML output
doc: RCU callback locks need only _bh, not necessarily _irq
docs: format kernel-parameters -- as code
Doc : doc-guide : Fix a typo
platform: x86: get rid of a non-existent document
Add the RCU docs to the core-api manual
Documentation: RCU: Add TOC tree hooks
Documentation: RCU: Rename txt files to rst
Documentation: RCU: Convert RCU UP systems to reST
Documentation: RCU: Convert RCU linked list to reST
Documentation: RCU: Convert RCU basic concepts to reST
docs: filesystems: Remove uneeded .rst extension on toctables
scripts/sphinx-pre-install: fix out-of-tree build
docs: zh_CN: submitting-drivers.rst: Remove a duplicated Documentation/
Documentation: PGP: update for newer HW devices
Documentation: Add section about CPU vulnerabilities for Spectre
Documentation: platform: Delete x86-laptop-drivers.txt
docs: Note that :c:func: should no longer be used
...
Diffstat (limited to 'Documentation/mic/mic_overview.rst')
-rw-r--r-- | Documentation/mic/mic_overview.rst | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/Documentation/mic/mic_overview.rst b/Documentation/mic/mic_overview.rst new file mode 100644 index 000000000000..17d956bdaf7c --- /dev/null +++ b/Documentation/mic/mic_overview.rst @@ -0,0 +1,85 @@ +====================================================== +Intel Many Integrated Core (MIC) architecture overview +====================================================== + +An Intel MIC X100 device is a PCIe form factor add-in coprocessor +card based on the Intel Many Integrated Core (MIC) architecture +that runs a Linux OS. It is a PCIe endpoint in a platform and therefore +implements the three required standard address spaces i.e. configuration, +memory and I/O. The host OS loads a device driver as is typical for +PCIe devices. The card itself runs a bootstrap after reset that +transfers control to the card OS downloaded from the host driver. The +host driver supports OSPM suspend and resume operations. It shuts down +the card during suspend and reboots the card OS during resume. +The card OS as shipped by Intel is a Linux kernel with modifications +for the X100 devices. + +Since it is a PCIe card, it does not have the ability to host hardware +devices for networking, storage and console. We provide these devices +on X100 coprocessors thus enabling a self-bootable equivalent +environment for applications. A key benefit of our solution is that it +leverages the standard virtio framework for network, disk and console +devices, though in our case the virtio framework is used across a PCIe +bus. A Virtio Over PCIe (VOP) driver allows creating user space +backends or devices on the host which are used to probe virtio drivers +for these devices on the MIC card. The existing VRINGH infrastructure +in the kernel is used to access virtio rings from the host. The card +VOP driver allows card virtio drivers to communicate with their user +space backends on the host via a device page. Ring 3 apps on the host +can add, remove and configure virtio devices. A thin MIC specific +virtio_config_ops is implemented which is borrowed heavily from +previous similar implementations in lguest and s390. + +MIC PCIe card has a dma controller with 8 channels. These channels are +shared between the host s/w and the card s/w. 0 to 3 are used by host +and 4 to 7 by card. As the dma device doesn't show up as PCIe device, +a virtual bus called mic bus is created and virtual dma devices are +created on it by the host/card drivers. On host the channels are private +and used only by the host driver to transfer data for the virtio devices. + +The Symmetric Communication Interface (SCIF (pronounced as skiff)) is a +low level communications API across PCIe currently implemented for MIC. +More details are available at scif_overview.txt. + +The Coprocessor State Management (COSM) driver on the host allows for +boot, shutdown and reset of Intel MIC devices. It communicates with a COSM +"client" driver on the MIC cards over SCIF to perform these functions. + +Here is a block diagram of the various components described above. The +virtio backends are situated on the host rather than the card given better +single threaded performance for the host compared to MIC, the ability of +the host to initiate DMA's to/from the card using the MIC DMA engine and +the fact that the virtio block storage backend can only be on the host:: + + +----------+ | +----------+ + | Card OS | | | Host OS | + +----------+ | +----------+ + | + +-------+ +--------+ +------+ | +---------+ +--------+ +--------+ + | Virtio| |Virtio | |Virtio| | |Virtio | |Virtio | |Virtio | + | Net | |Console | |Block | | |Net | |Console | |Block | + | Driver| |Driver | |Driver| | |backend | |backend | |backend | + +---+---+ +---+----+ +--+---+ | +---------+ +----+---+ +--------+ + | | | | | | | + | | | |User | | | + | | | |------|------------|--+------|------- + +---------+---------+ |Kernel | + | | | + +---------+ +---+----+ +------+ | +------+ +------+ +--+---+ +-------+ + |MIC DMA | | VOP | | SCIF | | | SCIF | | COSM | | VOP | |MIC DMA| + +---+-----+ +---+----+ +--+---+ | +--+---+ +--+---+ +------+ +----+--+ + | | | | | | | + +---+-----+ +---+----+ +--+---+ | +--+---+ +--+---+ +------+ +----+--+ + |MIC | | VOP | |SCIF | | |SCIF | | COSM | | VOP | | MIC | + |HW Bus | | HW Bus| |HW Bus| | |HW Bus| | Bus | |HW Bus| |HW Bus | + +---------+ +--------+ +--+---+ | +--+---+ +------+ +------+ +-------+ + | | | | | | | + | +-----------+--+ | | | +---------------+ | + | |Intel MIC | | | | |Intel MIC | | + | |Card Driver | | | | |Host Driver | | + +---+--------------+------+ | +----+---------------+-----+ + | | | + +-------------------------------------------------------------+ + | | + | PCIe Bus | + +-------------------------------------------------------------+ |