33 строки
1.5 KiB
Plaintext
33 строки
1.5 KiB
Plaintext
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Paravirt_ops
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============
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Linux provides support for different hypervisor virtualization technologies.
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Historically different binary kernels would be required in order to support
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different hypervisors, this restriction was removed with pv_ops.
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Linux pv_ops is a virtualization API which enables support for different
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hypervisors. It allows each hypervisor to override critical operations and
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allows a single kernel binary to run on all supported execution environments
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including native machine -- without any hypervisors.
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pv_ops provides a set of function pointers which represent operations
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corresponding to low level critical instructions and high level
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functionalities in various areas. pv-ops allows for optimizations at run
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time by enabling binary patching of the low-ops critical operations
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at boot time.
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pv_ops operations are classified into three categories:
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- simple indirect call
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These operations correspond to high level functionality where it is
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known that the overhead of indirect call isn't very important.
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- indirect call which allows optimization with binary patch
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Usually these operations correspond to low level critical instructions. They
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are called frequently and are performance critical. The overhead is
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very important.
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- a set of macros for hand written assembly code
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Hand written assembly codes (.S files) also need paravirtualization
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because they include sensitive instructions or some of code paths in
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them are very performance critical.
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