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12291656b1
Required for a coming patch where iohelper will operate on O_DIRECT fds. There, the user-space memory must be aligned to file system boundaries (at least 512, but using page-aligned works better, and some file systems prefer 64k). Made tougher by the fact that VIR_ALLOC won't work on void *, but posix_memalign won't work on char * and isn't available everywhere. This patch makes some simplifying assumptions - namely, output to an O_DIRECT fd will only be attempted on an empty seekable file (hence, no need to worry about preserving existing data on a partial block, and ftruncate will work to undo the effects of having to round up the size of the last block written), and input from an O_DIRECT fd will only be attempted on a complete seekable file with the only possible short read at EOF. * configure.ac (AC_CHECK_FUNCS_ONCE): Check for posix_memalign. * src/util/iohelper.c (runIO): Use aligned memory, and handle quirks of O_DIRECT on last write.
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>