linux-kernel - Large DMA alloc

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Message-ID: <CAEHaoC2BWe+0Ps2oU-0xPDLFYYKG-o9+_ynFgh7u3qqyRDtrTg@mail.gmail.com>
Date: Sun, 3 Aug 2025 13:59:24 +0300
From: Constantine Gavrilov <cgavrilov@...inidat.com>
To: linux-kernel@...r.kernel.org, Marek Szyprowski <m.szyprowski@...sung.com>, 
	Robin Murphy <robin.murphy@....com>, iommu@...ts.linux.dev
Subject: Large DMA alloc

I have been working on a set of kernel changes to facilitate IOMMU registrations
of large memory regions. The context of this work is working with PCIe devices
that have very large PCIe memory BARs (multi-terabyte sizes are possible) from
user-space. Large memory registrations happen in this context when the PCIe
memory BARs are registered for access by other devices (like DMA engines), and
when the application memory buffers are registered for access by the
PCIe devices.
Working from user-space typically involves a single registration of large areas
(application buffers and memory BARs) to avoid run-time performance penalty of
dynamic small registrations per IO.

The full list of patches is provided below:

[PATCH 0/8] Large DMA alloc/skip 32-bit alloc if size > 32-bit
[PATCH 1/8] Large DMA alloc/extend alloc APIs to use alignment
[PATCH 2/8] Large DMA alloc/do not align allocations to size
[PATCH 3/8] Large DMA alloc/add busy_regions sysfs attribute
[PATCH 4/8] Large DMA alloc/add APIs to query available range
[PATCH 5/8] Large DMA alloc/remove max32_alloc_size field
[PATCH 6/8] Large DMA alloc/alloc DMA addresses from the top
[PATCH 7/8] Large DMA alloc/low address limit in alloc funcs
[PATCH 8/8] Large DMA alloc/add min_dma_addr to device struct

Entire work is available at the master branch of the git repository
git@...hub.com:cgavrilov/linux.git, with the purpose of sharing the code for a
possible kernel merge.

The following messages will provide individual patches.

-- 
----------------------------------------
Constantine Gavrilov
System Architect and Platform Engineer
Infinidat
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