1 ========================== 2 ELF Note PowerPC Namespace 3 ========================== 4 5 The PowerPC namespace in an ELF Note of the kernel binary is used to store 6 capabilities and information which can be used by a bootloader or userland. 7 8 Types and Descriptors 9 --------------------- 10 11 The types to be used with the "PowerPC" namespace are defined in [#f1]_. 12 13 1) PPC_ELFNOTE_CAPABILITIES 14 15 Define the capabilities supported/required by the kernel. This type uses a 16 bitmap as "descriptor" field. Each bit is described below: 17 18 - Ultravisor-capable bit (PowerNV only). 19 20 .. code-block:: c 21 22 #define PPCCAP_ULTRAVISOR_BIT (1 << 0) 23 24 Indicate that the powerpc kernel binary knows how to run in an 25 ultravisor-enabled system. 26 27 In an ultravisor-enabled system, some machine resources are now controlled 28 by the ultravisor. If the kernel is not ultravisor-capable, but it ends up 29 being run on a machine with ultravisor, the kernel will probably crash 30 trying to access ultravisor resources. For instance, it may crash in early 31 boot trying to set the partition table entry 0. 32 33 In an ultravisor-enabled system, a bootloader could warn the user or prevent 34 the kernel from being run if the PowerPC ultravisor capability doesn't exist 35 or the Ultravisor-capable bit is not set. 36 37 References 38 ---------- 39 40 .. [#f1] arch/powerpc/include/asm/elfnote.h 41
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