Bug 1479251 - NFS over UDP does not work
NFS over UDP does not work
Status: NEW
Product: Fedora
Classification: Fedora
Component: kernel (Show other bugs)
26
x86_64 Linux
unspecified Severity high
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Assigned To: Kernel Maintainer List
Fedora Extras Quality Assurance
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Reported: 2017-08-08 04:06 EDT by Wolfgang Denk
Modified: 2017-09-19 00:02 EDT (History)
8 users (show)

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Description Wolfgang Denk 2017-08-08 04:06:38 EDT
Description of problem:

After upgrading from F24 to F26 a number of diskless clients (embedded systems) stopped working.  They load the kernel image and DTB over NFS, and/or mount the rootfs over NFS.  In both cases, NFS over UDP is used. For Linux mounting the rootfs thisis not really mandatory, but for the bootloader (U-Boot) fetching the kernel image it is, since U-Boot implements only UDP.

With F25 and F26, this stopped working.  Apparently the Linux kernel in these releases does not support NFS over UDP any more.

Version-Release number of selected component (if applicable):

kernel-4.11.12-200.fc25.x86_64
kernel-4.11.11-300.fc26.x86_64

How reproducible:

Always

Steps to Reproduce:
1. Easy test: try mounting a Filesystem over NFS using UDP protocol:

mount -o udp server:/dir /dir

Actual results:

# mount -o udp sisyphus:/opt/tmp /mnt/tmp
mount.nfs: requested NFS version or transport protocol is not supported

Expected results:

Mount should succeed.

Additional info:

This restriction is blocking a pretty large number of devices from booting.
Falling back F24 on the file server is not really an option as it is no longer maintained.
Comment 1 Catalin 2017-09-19 00:02:03 EDT
Hi,

I noticed the same behaviour when I upgraded from fc24 to fc26. NFS server hosted on fc26 does not seem to accept UDP connections. Not sure if this is a bug or this is how things are supposed to be. 

Thanks,
Catalin

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