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1==========================2ELF Note PowerPC Namespace3==========================4 5The PowerPC namespace in an ELF Note of the kernel binary is used to store6capabilities and information which can be used by a bootloader or userland.7 8Types and Descriptors9---------------------10 11The types to be used with the "PowerPC" namespace are defined in [#f1]_.12 13 1) PPC_ELFNOTE_CAPABILITIES14 15Define the capabilities supported/required by the kernel. This type uses a16bitmap as "descriptor" field. Each bit is described below:17 18- Ultravisor-capable bit (PowerNV only).19 20.. code-block:: c21 22 #define PPCCAP_ULTRAVISOR_BIT (1 << 0)23 24Indicate that the powerpc kernel binary knows how to run in an25ultravisor-enabled system.26 27In an ultravisor-enabled system, some machine resources are now controlled28by the ultravisor. If the kernel is not ultravisor-capable, but it ends up29being run on a machine with ultravisor, the kernel will probably crash30trying to access ultravisor resources. For instance, it may crash in early31boot trying to set the partition table entry 0.32 33In an ultravisor-enabled system, a bootloader could warn the user or prevent34the kernel from being run if the PowerPC ultravisor capability doesn't exist35or the Ultravisor-capable bit is not set.36 37References38----------39 40.. [#f1] arch/powerpc/include/asm/elfnote.h41 42