ELF Note PowerPC Namespace¶
The PowerPC namespace in an ELF Note of the kernel binary is used to storecapabilities and information which can be used by a bootloader or userland.
Types and Descriptors¶
The types to be used with the “PowerPC” namesapce are defined in[1].
- PPC_ELFNOTE_CAPABILITIES
Define the capabilities supported/required by the kernel. This type uses abitmap as “descriptor” field. Each bit is described below:
- Ultravisor-capable bit (PowerNV only).
#define PPCCAP_ULTRAVISOR_BIT (1 << 0)Indicate that the powerpc kernel binary knows how to run in anultravisor-enabled system.
In an ultravisor-enabled system, some machine resources are now controlledby the ultravisor. If the kernel is not ultravisor-capable, but it ends upbeing run on a machine with ultravisor, the kernel will probably crashtrying to access ultravisor resources. For instance, it may crash in earlyboot trying to set the partition table entry 0.
In an ultravisor-enabled system, a bootloader could warn the user or preventthe kernel from being run if the PowerPC ultravisor capability doesn’t existor the Ultravisor-capable bit is not set.