[U-Boot] [RFC PATCH v2 0/7] "Transient" (= export-restricted) environment vars

[Bernhard Nortmann]

This series evolved around the idea of introducing a new env_op
type to control (and possibly restrict) the export of variables.
This is especially useful if one wants to prevent dynamic
configuration information from ending up in a saved environment -
the 'classic' example being network setup with "dhcp" followed
by the "saveenv" command.

(The networking case is even further complicated by the fact
that users may actually wish to setup and save a static IP
configuration manually, which means that "locking up" the
corresponding variables right away isn't a viable solution.)

See also:
http://lists.denx.de/pipermail/u-boot/2015-September/227611.html
http://lists.denx.de/pipermail/u-boot/2016-April/250237.html
Pointed out by Joe Hershberger:
http://lists.denx.de/pipermail/u-boot/2010-May/071315.html
http://lists.denx.de/pipermail/u-boot/2010-June/073031.html

Regards, B. Nortmann

Changes in v2:
- Add "Reviewed-by" sjg
- Removed too narrow (flag & H_FORCE) expression, use "flag" directly
- Fixed outdated "env_flags_varaccess_lock" to the correct
  "env_flags_varaccess_system"

Bernhard Nortmann (7):
  env: Allow unconditional access if H_PROGRAMMATIC is set
  net: dm: Ignore unknown env_op_* constants
  env: Introduce "export" operation and (access flag) restriction
  env: Introduce "transient" and "system" access flags
  sunxi: env: flag fel_* environment vars as "system"
  env: Introduce setenv_transient() helper function
  env: Automatically mark dynamic configuration info as "do not export"

 cmd/net.c                      | 34 +++++++++++++++++-----------------
 cmd/nvedit.c                   | 24 +++++++++++++++++++++++-
 common/env_flags.c             | 21 ++++++++++++++++++---
 include/common.h               |  1 +
 include/configs/sunxi-common.h |  8 ++++++++
 include/env_flags.h            |  5 ++++-
 include/search.h               |  1 +
 lib/hashtable.c                |  3 +++
 net/eth-uclass.c               |  2 ++
 9 files changed, 77 insertions(+), 22 deletions(-)

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2.7.3