zephyr/lib/posix/options/Kconfig.device_io
Chris Friedt bc4374b5fe posix: deprecate POSIX_MAX_FDS and add POSIX_DEVICE_IO
The POSIX_MAX_FDS option does not correspond to any standard
POSIX option. It was used to define the size of the file
descriptor table, which is by no means exclusively used by
POSIX (also net, fs, ...).

POSIX_MAX_FDS is being deprecated in order to ensure that
Zephyr's POSIX Kconfig variables correspond to those defined in
the specification, as of IEEE 1003.1-2017. Namely,
POSIX_OPEN_MAX. CONFIG_POSIX_MAX_OPEN_FILES is being deprecated
for the same reason.

To mitigate any possible layering violations, that option is
not user selectable. It tracks the newly added
CONFIG_ZVFS_OPEN_MAX option, which is native to Zephyr.

With this deprecation, we introduce the following Kconfig
options that map directly to standard POSIX Option Groups by
simply removing "CONFIG_":

* CONFIG_POSIX_DEVICE_IO

Similarly, with this deprecation, we introduce the following
Kconfig options that map directly to standard POSIX Options by
simply removing "CONFIG":

* CONFIG_POSIX_OPEN_MAX

In order to maintain parity with the current feature set, we
introduce the following Kconfig options.

* CONFIG_POSIX_DEVICE_IO_ALIAS_CLOSE
* CONFIG_POSIX_DEVICE_IO_ALIAS_OPEN
* CONFIG_POSIX_DEVICE_IO_ALIAS_READ
* CONFIG_POSIX_DEVICE_IO_ALIAS_WRITE

Gate open(), close(), read(), and write() via the
CONFIG_POSIX_DEVICE_IO Kconfig option and move
implementations into device_io.c, to be conformant with the
spec.

Lastly, stage function names for upcoming ZVFS work, to be
completed as part of the LTSv3 Roadmap (e.g. zvfs_open(), ..).

Signed-off-by: Chris Friedt <cfriedt@tenstorrent.com>
2024-06-04 16:27:12 -05:00

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# Copyright (c) 2024 Tenstorrent AI ULC
#
# SPDX-License-Identifier: Apache-2.0
menu "POSIX device I/O"
config POSIX_DEVICE_IO
bool "POSIX device I/O [EXPERIMENTAL]"
default y if POSIX_API
select FDTABLE
select EXPERIMENTAL
help
Select 'y' here and Zephyr will provide an implementation of the POSIX_DEVICE_IO Option
Group such as FD_CLR(), FD_ISSET(), FD_SET(), FD_ZERO(), close(), fdopen(), fileno(), open(),
poll(), pread(), pselect(), pwrite(), read(), select(), and write().
For more informnation, please see
https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_subprofiles.html
if POSIX_DEVICE_IO
# These options are intended to be used for compatibility with external POSIX
# implementations such as those in Newlib or Picolibc.
config POSIX_DEVICE_IO_ALIAS_CLOSE
bool
help
Select 'y' here and Zephyr will provide an alias for close() as _close().
config POSIX_DEVICE_IO_ALIAS_OPEN
bool
help
Select 'y' here and Zephyr will provide an alias for open() as _open().
config POSIX_DEVICE_IO_ALIAS_READ
bool
help
Select 'y' here and Zephyr will provide an alias for read() as _read().
config POSIX_DEVICE_IO_ALIAS_WRITE
bool
help
Select 'y' here and Zephyr will provide an alias for write() as _write().
endif # POSIX_DEVICE_IO
config POSIX_OPEN_MAX
int
default ZVFS_OPEN_MAX
help
The maximum number of files that a process can have open at one time. This option is not
directly user-configurable but can be adjusted via CONFIG_ZVFS_OPEN_MAX.
For more information, please see
https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/limits.h.html
endmenu