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Merge branch 'topic/ppc-kvm' into next
Merge our ppc-kvm topic branch to bring in the Ultravisor support patches.
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========================== | ||
ELF Note PowerPC Namespace | ||
========================== | ||
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The PowerPC namespace in an ELF Note of the kernel binary is used to store | ||
capabilities and information which can be used by a bootloader or userland. | ||
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Types and Descriptors | ||
--------------------- | ||
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The types to be used with the "PowerPC" namesapce are defined in the | ||
include/uapi/asm/elfnote.h | ||
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1) PPC_ELFNOTE_CAPABILITIES | ||
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Define the capabilities supported/required by the kernel. This type uses a | ||
bitmap as "descriptor" field. Each bit is described below: | ||
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- Ultravisor-capable bit (PowerNV only). | ||
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#define PPCCAP_ULTRAVISOR_BIT (1 << 0) | ||
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Indicate that the powerpc kernel binary knows how to run in an | ||
ultravisor-enabled system. | ||
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In an ultravisor-enabled system, some machine resources are now controlled | ||
by the ultravisor. If the kernel is not ultravisor-capable, but it ends up | ||
being run on a machine with ultravisor, the kernel will probably crash | ||
trying to access ultravisor resources. For instance, it may crash in early | ||
boot trying to set the partition table entry 0. | ||
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In an ultravisor-enabled system, a bootloader could warn the user or prevent | ||
the kernel from being run if the PowerPC ultravisor capability doesn't exist | ||
or the Ultravisor-capable bit is not set. | ||
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References | ||
---------- | ||
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arch/powerpc/include/asm/elfnote.h | ||
arch/powerpc/kernel/note.S | ||
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