Messages in this thread | | | From | Punit Agrawal <> | Subject | [RFC 0/1] serdes: Add whitelist to bring back missing serial port | Date | Mon, 16 Dec 2019 13:08:24 +0900 |
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Hi,
While booting v5.5-rc1 on Apollo Lake based UP2[0], I ran into an issue with the primary serial port. The kernel is able to output to ttyS0 but systemd isn't able to raise a login prompt. On further investigation, it turns out that no serial device (/dev/ttyS0) is being created as the device is claimed by serdev sub-system.
The issue has been reported in a few different places[0][1]. A patch was proposed to solve the issue but there doesn't seem to be any further progress[2]. Feedback on the thread suggested implementing a whitelist based approach - which is what this RFC does.
With this patch, systemd is able to create a login prompt. The whitelist has intentionally been left blank as it's not clear which devices go in there.
Feedback welcome.
Thanks, Punit
[0] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=911831 [1] https://bugs.launchpad.net/ubuntu/+source/linux-oem/+bug/1769610 [2] https://marc.info/?l=linux-serial&m=152455861101408&w=2
Punit Agrawal (1): serdev: Only claim supported devices
drivers/tty/serdev/core.c | 8 ++++++++ 1 file changed, 8 insertions(+)
-- 2.24.0
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