b02002cc4c
With our current support for the new MIO PCI instructions, write combining/write back MMIO memory can be obtained via the pci_iomap_wc() and pci_iomap_wc_range() functions. This is achieved by using the write back address for a specific bar as provided in clp_store_query_pci_fn() These functions are however not widely used and instead drivers often rely on ioremap_wc() and ioremap_prot(), which on other platforms enable write combining using a PTE flag set through the pgrprot value. While we do not have a write combining flag in the low order flag bits of the PTE like x86_64 does, with MIO support, there is a write back bit in the physical address (bit 1 on z15) and thus also the PTE. Which bit is used to toggle write back and whether it is available at all, is however not fixed in the architecture. Instead we get this information from the CLP Store Logical Processor Characteristics for PCI command. When the write back bit is not provided we fall back to the existing behavior. Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Reviewed-by: Pierre Morel <pmorel@linux.ibm.com> Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> |
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| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.