mbox series

[Concept,00/16] Introduce a pager for the console

Message ID 20250822142153.3404275-1-sjg@u-boot.org
Headers
Series Introduce a pager for the console |

Message

Simon Glass Aug. 22, 2025, 2:21 p.m. UTC 
  From: Simon Glass <sjg@chromium.org>

Some U-Boot commands can produce a lot of output and this can run off
top of the display. This series introduces a simple pager feature, to
allow the output to be read, before pressing SPACE to continue.

A fixed buffer size (4K) is used, which sets a limit on the permmited
output before paging fails and the output is simply written all in one
lot. In most cases this is plenty, but 'env print' does print the whole
environment as one string, so if the legacy distro-boot scripts are used
it could happen.

The default number of visible lines is set with a Kconfig option. Where
a video terminal is being used, the page size is set to match that. In
general U-Boot cannot guess the number of visible lines, since a serial
terminal may be in use.

There is also a 'pager' environment variable which can override any
detected value.

This initial series only counts newlines. It has no support for counting
characters so the result will be sub-optimal if very long lines are
written. This could be addressed in a future patch.

Future work may detect the terminal size by sending an ANSI sequence.


Simon Glass (16):
  console: Add the basic pager implementation
  console: Add tests for the basic functionality
  console: Provide a way to output without the pager
  console: Rename console-put functions to prepare for pager
  console: Plumb in the pager
  console: test: Allow tests to bypass the pager
  console: Support paging with single characters
  console: Add a few more paging tests
  console: Reset the pager when entering a new command
  console: Implement an environment var to control the pager
  console: Get the pager lines from the vidconsole
  efi: Enable the console pager for the app
  doc: Remove obsolete text in README.console
  doc: Move console docs to rST
  doc: Tidy up the console docs a little
  pager: doc: Add mention of the pager feature

 common/Kconfig                    |  20 ++
 common/Makefile                   |   2 +
 common/cli_readline.c             |  13 +-
 common/console.c                  |  99 +++--
 common/pager.c                    | 208 +++++++++++
 doc/README.console                | 100 ------
 doc/usage/console.rst             |  78 ++++
 doc/usage/environment.rst         |   8 +
 doc/usage/index.rst               |   1 +
 include/asm-generic/global_data.h |  11 +
 include/env_callback.h            |   7 +
 include/pager.h                   | 178 +++++++++
 lib/efi_client/Kconfig            |   1 +
 test/common/Makefile              |   1 +
 test/common/pager.c               | 576 ++++++++++++++++++++++++++++++
 test/test-main.c                  |   3 +
 16 files changed, 1183 insertions(+), 123 deletions(-)
 create mode 100644 common/pager.c
 delete mode 100644 doc/README.console
 create mode 100644 doc/usage/console.rst
 create mode 100644 include/pager.h
 create mode 100644 test/common/pager.c