[Letux-kernel] MIPS: bug: gettimeofday syscall broken on CI20 board?

H. Nikolaus Schaller hns at goldelico.com
Thu Nov 7 17:21:13 CET 2019

I am trying to run v5.4-rc6 on the CI20 board (jz4780) and it
is almost ok. Except one strange thing.

If I install a v4.19.81 kernel I can initialize the
ethernet interface and dhclient works.

If I install a v5.4-rc6 kernel on exactly the same
rootfs dhclient fails with

root at letux:~# dhclient
../../../../lib/isc/unix/time.c:200: Operation not permitted
root at letux:~#

I have done some strace and the first significant difference
is that with v5.4-rc6 there is no gettimeofday syscall.

Another symptom pointing in the same direction is that
after manually assigning an IP address I can run ping
but get strange time values.

So it may be that

24640f233b46 mips: Add support for generic vDSO

did break gettimeofday when used with latest Debian Stretch
libraries. I tried to git revert but there are conflicts.

Just a side-note: both kernels work with Debian Jessie,
which likely has an older gettimeofday wrapper that
is not influenced by some subtle change.

BR and thanks,
Nikolaus Schaller

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