Re: Bug#854588: debian-installer: recognize arrow keys as esc in serial console
Hi!
On 03/15/2017 10:45 AM, John Paul Adrian Glaubitz wrote:
>> For most keys, it seems works well, while when press
>> arrow keys "up"/"down"/"left"/"right",
>> they are recognized as 'ESC' key.
>
> We are seeing this issue on sparc64 now as well when using a serial
> console for the installation. Using the arrow keys in the serial
> console leads to random key presses (not sure whether it's <ESC>
> or <RETURN> here), it did work fine in the past.
Michael Karcher (CC'ed) has had a go at this and it seems it is an issue
with the serial connection dropping some characters during transmission.
Since the cursor keys generate escape sequences in the terminal, the
transmission for a cursor key press needs to be stable over several
characters.
Invoking "infocmp ansi" will print out the escape sequences for various
terminal actions. The cursor movement is controlled by these sequences:
cr=^M, cub=\E[%p1%dD, cub1=\E[D, cud=\E[%p1%dB, cud1=\E[B,
cuf=\E[%p1%dC, cuf1=\E[C, cup=\E[%i%p1%d;%p2%dH,
cuu=\E[%p1%dA, cuu1=\E[A, dch=\E[%p1%dP, dch1=\E[P,
As you can see, these sequences usually involve <ESCAPE> plus additional
characters. So, what happens in the case of Debian installer is that the
characters after the <ESCAPE> are dropped and instead of the escape sequence,
the terminal application (debian-installer) is receiving <ESCAPE> only
which results in an escape key press.
As possible cause for the issue might be a bug in the FIFO implementation
of the serial connection. Michael will hopefully correct me if I am wrong.
Thanks,
Adrian
--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer - glaubitz@debian.org
`. `' Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
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