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[Xen-devel] [PATCH 0/3] [RFC] User-space grant table device

I've completed a version of a Linux kernel driver for mapping granted pages into user-space. There are a few use cases for this, but the most important (from a XenSE/dom0 disaggregation point of view) is changing the way the the console daemon and xenstore map their respective pages in the guests. A further possibility might be reimplementing blktap entirely in user-space.

Currently the driver supports:
* Mapping one or more pages at a time into a contiguous portion of memory.. * Mapping up to 128 pages per file descriptor (this is an arbitrary limit, but it would be trivial to make this configurable). * Each page may only be mapped once. However, it is possible to map the same grant more than once: simply register the grant twice with the ioctl, and then map the two (different) offsets.

In addition, I've written some simple libxc functions (of the same format as the xc_evtchn_* functions) that provide access to the driver.

I've split up the patch as follows:

1. gntdev.patch: This is the main driver, and associated header file.
2. libxc-changes.patch: These are the libxc functions for accessing the driver. 3. linux-changes.patch: These contain the necessary changes to linux (in effect, adding a hook to the vm_operations_struct that is called by the unmap_page_range function) for unmapping grants before the page table is destroyed.

I'd welcome your comments.


Derek Murray.

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