a00e8502c9
Update documentation to reflect the branch changes. Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
60 lines
3 KiB
Markdown
60 lines
3 KiB
Markdown
# Maintained branches
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At any point in time, we have a number of maintained branches consisting of:
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- The [`master`](https://github.com/ARMmbed/mbedtls/tree/master) branch:
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this always contains the latest release, including all publicly available
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security fixes.
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- The [`development`](https://github.com/ARMmbed/mbedtls/tree/development) branch:
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this is where the next major version of Mbed TLS (version 3.0) is being
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prepared. It has API changes that make it incompatible with Mbed TLS 2.x,
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as well as all the new features and bug fixes and security fixes.
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- The [`development_2.x`](https://github.com/ARMmbed/mbedtls/tree/development_2.x) branch:
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this branch retains the API of Mbed TLS 2.x, and has a subset of the
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features added after Mbed TLS 2.26.0 and bug fixes and security fixes.
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- One or more long-time support (LTS) branches:
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these only get bug fixes and security fixes.
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We use [Semantic Versioning](https://semver.org/). In particular, we maintain
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API compatibility in the `master` branch between major version changes. We
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also maintain ABI compatibility within LTS branches; see the next section for
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details.
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## Backwards Compatibility
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We maintain API compatibility in released versions of Mbed TLS. If you have
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code that's working and secure with Mbed TLS x.y.z and does not rely on
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undocumented features, then you should be able to re-compile it without
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modification with any later release x.y'.z' with the same major version
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number, and your code will still build, be secure, and work.
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There are rare exceptions: code that was relying on something that became
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insecure in the meantime (for example, crypto that was found to be weak) may
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need to be changed. In case security comes in conflict with backwards
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compatibility, we will put security first, but always attempt to provide a
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compatibility option.
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For the LTS branches, additionally we try very hard to also maintain ABI
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compatibility (same definition as API except with re-linking instead of
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re-compiling) and to avoid any increase in code size or RAM usage, or in the
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minimum version of tools needed to build the code. The only exception, as
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before, is in case those goals would conflict with fixing a security issue, we
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will put security first but provide a compatibility option. (So far we never
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had to break ABI compatibility in an LTS branch, but we occasionally had to
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increase code size for a security fix.)
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For contributors, see the [Backwards Compatibility section of
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CONTRIBUTING](CONTRIBUTING.md#cackwords-compatibility).
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## Current Branches
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The following branches are currently maintained:
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- [master](https://github.com/ARMmbed/mbedtls/tree/master)
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- [`development`](https://github.com/ARMmbed/mbedtls/)
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- [`development_2.x`](https://github.com/ARMmbed/mbedtls/tree/development_2.x)
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- [`mbedtls-2.16`](https://github.com/ARMmbed/mbedtls/tree/mbedtls-2.16)
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maintained until at least the end of 2021, see
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<https://tls.mbed.org/tech-updates/blog/announcing-lts-branch-mbedtls-2.16>
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Users are urged to always use the latest version of a maintained branch.
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