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A minority of page table implementations (arm_lpae, armv7) are unique in how they handle partial unmap of large IOPTEs. Other implementations will unmap the large IOPTE and return it's length. For example if a 2M IOPTE is present and the first 4K is requested to be unmapped then unmap will remove the whole 2M and report 2M as the result. armv7 instead will break up contiguous entries and replace an entry with a whole table so it can unmap the requested 4k. This seems copied from the arm_lpae implementation, which was analyzed here: https://lore.kernel.org/all/20241024134411.GA6956@nvidia.com/ Bring consistency to the implementations and remove this unused functionality. There are no uses outside iommu, this effects the ARM_V7S drivers msm_iommu, mtk_iommu, and arm-smmmu. Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Link: https://lore.kernel.org/r/2-v3-b3a5b5937f56+7bb-arm_no_split_jgg@nvidia.com [will: Remove unused 'loopnr' variable] Signed-off-by: Will Deacon <will@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 reStructuredText 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.