Gentoo Archives: gentoo-user

From: Alan Mackenzie <acm@×××.de>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] Console scrollback
Date: Wed, 20 Jan 2021 19:59:18
Message-Id: YAiLjZKM9eGrZjY2@ACM
In Reply to: Re: [gentoo-user] Console scrollback by Laurence Perkins
1 Hello, Laurence.
2
3 On Tue, Jan 19, 2021 at 17:09:03 +0000, Laurence Perkins wrote:
4
5
6 > On Sun, 2021-01-17 at 05:17 +0000, Thomas Mueller wrote:
7 > > On Sat, 16 Jan 2021 12:01:48 +0000, Alan Mackenzie wrote:
8
9 > > > I don't know what I'll be doing, long term. For the moment, I'll
10 > > > be hanging onto the working kernel I've got, old though it may be
11 > > > (4.19.97). It might be possible (I'm not sure) to hook up a user
12 > > > space program to the keys <shift>-<PageUp/Down> which would take
13 > > > care of the scrolling. This would obviously not work with early
14 > > > kernel messages, but would be better than nothing. I had a look at
15 > > > the GNU screen source code yesterday to see how it managed such
16 > > > things, but it is very sparsely commented, and thus hard work to
17 > > > understand. Maybe I should just cut my losses, and convert to
18 > > > using one of the BSDs.
19
20 > > 2000 posts per day on Linux kernel list would be more than
21 > > unmanageable for me! I wouldn't say "almost"!
22
23 > > Is Linus Torvalds' removal of console scrolling the reason why Scroll
24 > > Lock does not work on the console with System Rescue CD or USB, while
25 > > with FreeBSD and NetBSD, I can press Scroll Lock and scroll back?
26
27 > > I like that ability but don't think Linus Torvalds is listening or
28 > > reading this.
29
30 > > Further, with System Rescue console, the lines/text go only partway
31 > > down.
32
33 > > Using screen, now at v4.8, means having to remember a lot of key
34 > > functions, you need a separate reference screen to look them up.
35
36 > > There is also tmux, which is part of the base system in NetBSD but
37 > > not FreeBSD.
38
39 > > If Linus cared about his users, he could make the kernel headers more
40 > > user-friendly, installing kernel headers should not be any more
41 > > complicated than copying or downloading.
42
43 > > Console scrolling is especially useful with an OS or distro that is
44 > > built from the ground up, like Gentoo, Void or Arch, as opposed to
45 > > being installed all at once.
46
47 > > If more Linux users would go to and try NetBSD or FreeBSD, those OSes
48 > > would have more users, more ideas, more ability to improve.
49
50 > > You can even cross-compile NetBSD from Linux. You'd need NetBSD
51 > > source tree, but don't have to do anything special to install kernel
52 > > headers.
53
54 > > Tom
55
56
57 > You're getting this second-hand since it was my brother who actually
58 > looked into it, so pardon anything I misremember, but the big problem
59 > is that adding unicode support to vgacon would need a near total
60 > rewrite, and nobody wants to do that since it's a terrible hackjob to
61 > start with.
62
63 > kmscon is slated to be the replacement. You might want to see if that
64 > can do what you need.
65
66 I looked kmscon up on Wikipedia, and apparently development ceased
67 several years ago.
68
69 What I have in mind now is writing a Linux driver, a small piece of code
70 which would piggy-back on the existing virtual terminal drivers, and
71 simply pass everything through to and from the main driver, filtering out
72 things relevant to scrolling, and processing these in my new driver.
73 I've spent the last few evenings reading up on drivers, and reading the
74 relevant source code from 4.19.97. I can understand the kernel
75 maintainers not being enthusiastic about the existing code. But that
76 dates from, I believe, the 1990s, when RAM was measured in megabytes, and
77 processor speeds in megahertz. Optimisation for speed and store usage
78 just isn't important any more.
79
80 > LMP
81
82 --
83 Alan Mackenzie (Nuremberg, Germany).

Replies

Subject Author
Re: [gentoo-user] Console scrollback Wols Lists <antlists@××××××××××××.uk>
Re: [gentoo-user] Console scrollback Alan Mackenzie <acm@×××.de>