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all: require Linux 3.17 kernel for Go 1.24 #67001

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rsc opened this issue Apr 23, 2024 · 15 comments
Open

all: require Linux 3.17 kernel for Go 1.24 #67001

rsc opened this issue Apr 23, 2024 · 15 comments

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@rsc
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rsc commented Apr 23, 2024

In 2021 in #45964 we moved the minimum Linux kernel version to 2.6.32.

There is a good summary from @baryluk about what we use from newer kernels at #60792 (comment).

@mdempsky points out in #60792 (comment) that Rust and glibc decided on a minimum kernel version of 3.2 last year.

Adopting 3.2 as Go's minimum seems reasonable given the rest of the Linux ecosystem doing the same.

I propose we announce this in Go 1.23 and make the change in Go 1.24. That will still be a year or so behind glibc and Rust, and the announcement will create time for people to speak up if they are affected and cannot upgrade.

Really everyone should be on newer kernels for security updates anyway.

@robpike
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robpike commented Apr 23, 2024

I'm ambivalent about this trend in general. For Go, it also pushes a bit against the compatibility promise.

I've been burned multiple times by manufacturers dropping support for old hardware, requiring expensive upgrade purchases that provide no return benefit to me. I still run a 32-bit x86 Mac in the lab because without it I cannot control an important piece of kit that can only be interfaced to an old mac OS version. I can't even connect it to the network for fear some update will render my equipment non-working.

While I appreciate the implied - if uncertain - value of "newer is safer, newer is better", what is the actual cost to the project of letting Go binaries run on old OSes? That seems a better way to evaluate this proposal.

@rsc
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rsc commented Apr 23, 2024

The cost to the project in general is continued maintenance and testing of code paths working around the lack of features from the (relatively) newer kernels. We don't do a great job of testing Go on these old kernels as it is. It probably only kind of works.

I should have mentioned that Linux 3.2 was released 12 years ago. It is not bleeding edge by any means. According to https://en.wikipedia.org/wiki/Linux_kernel_version_history, the final 2.6.x kernel was 2.6.32.71 in 2016.

We are talking about dropping support for kernels that are very old.

@rsc
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rsc commented Apr 24, 2024

Talking to @FiloSottile about #66821, it sounds like moving to 3.17 (~2014) as the minimum would let us avoid needing to open /dev/urandom ever, because 3.17 added getrandom(2). That would be a better choice than 3.2.

@rsc rsc changed the title proposal: all: require Linux 3.2 kernel for Go 1.24 proposal: all: require Linux 3.17 kernel for Go 1.24 Apr 24, 2024
@rsc
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rsc commented Apr 24, 2024

This proposal has been added to the active column of the proposals project
and will now be reviewed at the weekly proposal review meetings.
— rsc for the proposal review group

@tianon
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tianon commented Apr 24, 2024

In the way of additional data points, a few popular and older distribution versions and their associated kernel versions (all of which IMO point in favor of this proposal at 3.2 and even at 3.17 👍):

  • Debian 10 (Buster): 4.19
  • Ubuntu 20.04 (focal): 5.4 (you have to go all the way back to 14.04 to get 3.13 / incompatible)
  • CentOS 7: 3.10 (but, 7 is fully EOL on 2024-06-30 in two short months)
  • CentOS 8: 4.18 (EOL 2021-12-31)
  • Fedora 38: 6.2
  • OpenWrt 22.03: 5.10 (EOL 2024-04-11)

It's a bit hard to browse, but even more aggregated data at https://repology.org/project/linux/versions

(I dug up this information to convince myself this was sane and figured it was worth sharing 👍 ❤️)

Edit: and see #60792 (comment) for a much longer form of similar data with many more details! 😄 ❤️

@ulikunitz
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ulikunitz commented Apr 24, 2024

Red Hat Enterprise Linux 7 is on kernel 3.10 and it's maintenance ends 30 June 2024. Red Hat offers Extended Lifecycle Support until 30 June 2028. Gcloud CLI supports RHEL7 and it includes Golang binaries. You may want to clarify how long Gcloud CLI plans to support RHEL7.

@empire
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empire commented Apr 24, 2024

The RHEL 7.9 OS has a kernel version 3.10.0 and is supported until 2028-06. Changing the minimum version to 3.17 may impact services running on this OS.

https://distrowatch.com/table.php?distribution=redhat&pkglist=true&version=rhel-7.9#pkglist

@AGWA
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AGWA commented Apr 24, 2024

The RHEL 7 kernel had getrandom backported in 2017, per https://access.redhat.com/errata/RHSA-2017:1842:

BZ - 1330000 - kernel: Backport getrandom system call

So in practice Go programs would continue to work on RHEL 7 if the only 3.10+ feature used is getrandom.

@rsc
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rsc commented Apr 25, 2024

Thanks for the added details. I think we can say 3.10+getrandom is fine too.

@rsc
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rsc commented May 8, 2024

Have all remaining concerns about this proposal been addressed?

The proposal is to require Linux 3.17 starting in Go 1.24,
with the exception that Linux 3.10 patched with an added getrandom(2) system call is also permitted.

@baryluk
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baryluk commented May 12, 2024

I think 3.17 (or 3.10+getrandom) is doable and reasonable.

I had a minor concern with Debian 8 codename Jessie, released April 2015, which is still in extended long term support by freexian (paid support, until mid 2025, possibly mid 2026 at most if customers pay for it), because it had 3.16.7.

But even during normal LTS there were backports available with kernel 4.9, and now freexian recommends their backports (due to security updates mostly) maintained by them of kernel 4.19 and 5.10. And anybody still running so old system (initial release 2015-04-26, official EOL 2020-07; and now we are at Debian 12, so many many major releases behind), can just stick to old code, or continue using older Go to maintain any software they run.

So even Debian 8 with ELTS would be fine with this 3.17+ requirement in practice. (Debian 9 codename Stretch, was released with 4.9.30, on 2017-06-18, already out of normal LTS, and ELTS from freexian until 2027).

So, good to go with 3.17

@rsc
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rsc commented May 15, 2024

Based on the discussion above, this proposal seems like a likely accept.
— rsc for the proposal review group

The proposal is to require Linux 3.17 starting in Go 1.24,
with the exception that Linux 3.10 patched with an added getrandom(2) system call is also permitted.

@rsc
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rsc commented May 23, 2024

No change in consensus, so accepted. 🎉
This issue now tracks the work of implementing the proposal.
— rsc for the proposal review group

The proposal is to require Linux 3.17 starting in Go 1.24,
with the exception that Linux 3.10 patched with an added getrandom(2) system call is also permitted.

@rsc rsc changed the title proposal: all: require Linux 3.17 kernel for Go 1.24 all: require Linux 3.17 kernel for Go 1.24 May 23, 2024
@rsc rsc modified the milestones: Proposal, Backlog May 23, 2024
@dmitshur dmitshur modified the milestones: Backlog, Go1.24 May 23, 2024
@gopherbot
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Change https://go.dev/cl/588216 mentions this issue: internal/poll,syscall: drop the fallback for accept4 on linux/arm

@gopherbot
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Change https://go.dev/cl/589015 mentions this issue: doc/next: preannounce a new Linux kernel version requirement

gopherbot pushed a commit that referenced this issue May 30, 2024
This change adds a preannouncement to the release notes. Go 1.24
will require the Linux kernel to be at version 3.17 or later,
with an exception that systems running 3.10 or later will
continue to be supported if the kernel has been patched to
support the getrandom system call.

For #65614
For #67001

Change-Id: I61a3838b9ce4f48eb9f94830aa03372d589afdcd
Reviewed-on: https://go-review.googlesource.com/c/go/+/589015
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
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