summaryrefslogtreecommitdiffstats
path: root/kernel/Documentation/mic/mic_overview.txt
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/Documentation/mic/mic_overview.txt')
-rw-r--r--kernel/Documentation/mic/mic_overview.txt66
1 files changed, 66 insertions, 0 deletions
diff --git a/kernel/Documentation/mic/mic_overview.txt b/kernel/Documentation/mic/mic_overview.txt
new file mode 100644
index 000000000..77c541802
--- /dev/null
+++ b/kernel/Documentation/mic/mic_overview.txt
@@ -0,0 +1,66 @@
+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.
+
+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.
+
+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 +--------------------------+
+ | | | Virtio over PCIe IOCTLs |
+ | | +--------------------------+
++-----------+ | | | +-----------+
+| MIC DMA | | | | | MIC DMA |
+| Driver | | | | | Driver |
++-----------+ | | | +-----------+
+ | | | | |
++---------------+ | | | +----------------+
+|MIC virtual Bus| | | | |MIC virtual Bus |
++---------------+ | | | +----------------+
+ | | | | |
+ | +--------------+ | +---------------+ |
+ | |Intel MIC | | |Intel MIC | |
+ +---|Card Driver | | |Host Driver | |
+ +--------------+ | +---------------+-----+
+ | | |
+ +-------------------------------------------------------------+
+ | |
+ | PCIe Bus |
+ +-------------------------------------------------------------+