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From: "xuyang2018.jy@fujitsu.com" <xuyang2018.jy@fujitsu.com>
To: "linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>
Subject: the usage of hardware flow control in serial console
Date: Tue, 1 Jun 2021 02:39:41 +0000	[thread overview]
Message-ID: <60B59E0F.7030609@fujitsu.com> (raw)

HI All

I append "console=ttyS0,115200n8r" to my kernel command line and reboot
my system.

# cat /proc/tty/driver/serial
serinfo:1.0 driver revision:
0: uart:16550A port:000003F8 irq:4 tx:0 rx:0 RTS|DTR
1: uart:unknown port:000002F8 irq:3
2: uart:unknown port:000003E8 irq:4
3: uart:unknown port:000002E8 irq:3

then I echo 1 > /dev/ttyS0, but it hangs.(If I don't use r, it works well.)
Does it need my console connected with other machine?
Also, many services become timeout when I use systemctl
restart/status/stop(tx,rx data doesn't increase).

I just want to check whether it is a usage problem(my system environmet
is centos8). My machine is physical machine and virtual machine doesn't
have this problem(it has RTS|CTS|DTR|DSR|CD flag).

Best Regards
Yang Xu

             reply	other threads:[~2021-06-01  2:46 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-01  2:39 xuyang2018.jy [this message]
2021-06-01  4:49 ` the usage of hardware flow control in serial console Greg KH

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