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By default on PPC32 PCI bus numbers are unique across all PCI domains. So a system could have only 256 PCI buses independently of available PCI domains. This is due to filling DT property pci-OF-bus-map which does not support a multi-domain setup. On all powerpc platforms except chrp and powermac there is no DT property pci-OF-bus-map anymore and therefore it is possible on non-chrp/powermac platforms to avoid this limitation of maximum number of 256 PCI buses in a system even on multi-domain setup. But avoiding this limitation would mean that all PCI and PCIe devices would be present on completely different BDF addresses as every PCI domain starts numbering PCI bueses from zero (instead of the last bus number of previous enumerated PCI domain). Such change could break existing software which expects fixed PCI bus numbers. So add a new config option CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT which enables this change. By default it is disabled. It causes the initial value of hose->first_busno to be zero. Signed-off-by: Pali Rohár <pali@kernel.org> [mpe: Minor change log wording] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220706104308.5390-6-pali@kernel.org
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.