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Diffstat (limited to 'kernel/Documentation/mic/mic_overview.txt')
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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 | + +-------------------------------------------------------------+ |