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authorLinus Torvalds <torvalds@linux-foundation.org>2022-12-30 03:57:29 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-12-30 03:57:29 +0300
commitbff687b3dad6e0e56b27f4d3ed8a9695f35c7b1a (patch)
tree03182056b8409e0d7bb9914663f60ef4496338c5 /Documentation
parentac787ffa5a246e53675ae93294420ea948600818 (diff)
parent1551ed5a178ca030adc92b1eb29157b5e92bf134 (diff)
downloadlinux-bff687b3dad6e0e56b27f4d3ed8a9695f35c7b1a.tar.xz
Merge tag 'block-6.2-2022-12-29' of git://git.kernel.dk/linux
Pull block fixes from Jens Axboe: "Mostly just NVMe, but also a single fixup for BFQ for a regression that happened during the merge window. In detail: - NVMe pull requests via Christoph: - Fix doorbell buffer value endianness (Klaus Jensen) - Fix Linux vs NVMe page size mismatch (Keith Busch) - Fix a potential use memory access beyong the allocation limit (Keith Busch) - Fix a multipath vs blktrace NULL pointer dereference (Yanjun Zhang) - Fix various problems in handling the Command Supported and Effects log (Christoph Hellwig) - Don't allow unprivileged passthrough of commands that don't transfer data but modify logical block content (Christoph Hellwig) - Add a features and quirks policy document (Christoph Hellwig) - Fix some really nasty code that was correct but made smatch complain (Sagi Grimberg) - Use-after-free regression in BFQ from this merge window (Yu)" * tag 'block-6.2-2022-12-29' of git://git.kernel.dk/linux: nvme-auth: fix smatch warning complaints nvme: consult the CSE log page for unprivileged passthrough nvme: also return I/O command effects from nvme_command_effects nvmet: don't defer passthrough commands with trivial effects to the workqueue nvmet: set the LBCC bit for commands that modify data nvmet: use NVME_CMD_EFFECTS_CSUPP instead of open coding it nvme: fix the NVME_CMD_EFFECTS_CSE_MASK definition docs, nvme: add a feature and quirk policy document nvme-pci: update sqsize when adjusting the queue depth nvme: fix setting the queue depth in nvme_alloc_io_tag_set block, bfq: fix uaf for bfqq in bfq_exit_icq_bfqq nvme: fix multipath crash caused by flush request when blktrace is enabled nvme-pci: fix page size checks nvme-pci: fix mempool alloc size nvme-pci: fix doorbell buffer value endianness
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/maintainer/maintainer-entry-profile.rst1
-rw-r--r--Documentation/nvme/feature-and-quirk-policy.rst77
2 files changed, 78 insertions, 0 deletions
diff --git a/Documentation/maintainer/maintainer-entry-profile.rst b/Documentation/maintainer/maintainer-entry-profile.rst
index 93b2ae6c34a9..cfd37f31077f 100644
--- a/Documentation/maintainer/maintainer-entry-profile.rst
+++ b/Documentation/maintainer/maintainer-entry-profile.rst
@@ -104,3 +104,4 @@ to do something different in the near future.
../riscv/patch-acceptance
../driver-api/media/maintainer-entry-profile
../driver-api/vfio-pci-device-specific-driver-acceptance
+ ../nvme/feature-and-quirk-policy
diff --git a/Documentation/nvme/feature-and-quirk-policy.rst b/Documentation/nvme/feature-and-quirk-policy.rst
new file mode 100644
index 000000000000..c01d836d8e41
--- /dev/null
+++ b/Documentation/nvme/feature-and-quirk-policy.rst
@@ -0,0 +1,77 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======================================
+Linux NVMe feature and and quirk policy
+=======================================
+
+This file explains the policy used to decide what is supported by the
+Linux NVMe driver and what is not.
+
+
+Introduction
+============
+
+NVM Express is an open collection of standards and information.
+
+The Linux NVMe host driver in drivers/nvme/host/ supports devices
+implementing the NVM Express (NVMe) family of specifications, which
+currently consists of a number of documents:
+
+ - the NVMe Base specification
+ - various Command Set specifications (e.g. NVM Command Set)
+ - various Transport specifications (e.g. PCIe, Fibre Channel, RDMA, TCP)
+ - the NVMe Management Interface specification
+
+See https://nvmexpress.org/developers/ for the NVMe specifications.
+
+
+Supported features
+==================
+
+NVMe is a large suite of specifications, and contains features that are only
+useful or suitable for specific use-cases. It is important to note that Linux
+does not aim to implement every feature in the specification. Every additional
+feature implemented introduces more code, more maintenance and potentially more
+bugs. Hence there is an inherent tradeoff between functionality and
+maintainability of the NVMe host driver.
+
+Any feature implemented in the Linux NVMe host driver must support the
+following requirements:
+
+ 1. The feature is specified in a release version of an official NVMe
+ specification, or in a ratified Technical Proposal (TP) that is
+ available on NVMe website. Or if it is not directly related to the
+ on-wire protocol, does not contradict any of the NVMe specifications.
+ 2. Does not conflict with the Linux architecture, nor the design of the
+ NVMe host driver.
+ 3. Has a clear, indisputable value-proposition and a wide consensus across
+ the community.
+
+Vendor specific extensions are generally not supported in the NVMe host
+driver.
+
+It is strongly recommended to work with the Linux NVMe and block layer
+maintainers and get feedback on specification changes that are intended
+to be used by the Linux NVMe host driver in order to avoid conflict at a
+later stage.
+
+
+Quirks
+======
+
+Sometimes implementations of open standards fail to correctly implement parts
+of the standards. Linux uses identifier-based quirks to work around such
+implementation bugs. The intent of quirks is to deal with widely available
+hardware, usually consumer, which Linux users can't use without these quirks.
+Typically these implementations are not or only superficially tested with Linux
+by the hardware manufacturer.
+
+The Linux NVMe maintainers decide ad hoc whether to quirk implementations
+based on the impact of the problem to Linux users and how it impacts
+maintainability of the driver. In general quirks are a last resort, if no
+firmware updates or other workarounds are available from the vendor.
+
+Quirks will not be added to the Linux kernel for hardware that isn't available
+on the mass market. Hardware that fails qualification for enterprise Linux
+distributions, ChromeOS, Android or other consumers of the Linux kernel
+should be fixed before it is shipped instead of relying on Linux quirks.