acassis commented on code in PR #11044:
URL: https://github.com/apache/nuttx/pull/11044#discussion_r1371877205
##########
Documentation/components/filesystem/cromfs.rst:
##########
@@ -0,0 +1,254 @@
+======
+cromfs
+======
+
+Overview
+========
+
+This directory contains the the CROMFS file system. This is an in-memory
+(meaning no block driver), read-only (meaning that can lie in FLASH) file
+system. It uses LZF decompression on data only (meta data is not
+compressed).
+
+It accesses the in-memory file system via directory memory reads and, hence,
+can only reside in random access NOR-like FLASH. It is intended for use
+with on-chip FLASH available on most MCUs (the design could probably be
+extended to access non-random-access FLASH as well, but those extensions
+are not yet in place).
+
+I do not have a good way to measure how much compression we get using LZF.
+I have seen 37% compression reported in other applications, so I have to
+accept that for now. That means, for example, that you could have a file
+system with 512Kb of data in only 322Kb of FLASH, giving you 190Kb to do
+other things with.
+
+LZF compression is not known for its high compression ratios, but rather
+for fast decompression. According to the author of the LZF decompression
+routine, it is nearly as fast as a memcpy!
+
+There is also a new tool at /tools/gencromfs.c that will generate binary
+images for the NuttX CROMFS file system and and an example CROMFS file
+system image at apps/examples/cromfs. That example includes a test file
+system that looks like::
+
+ $ ls -Rl ../apps/examples/cromfs/cromfs
+ ../apps/examples/cromfs/cromfs:
+ total 2
+ -rwxr--r--+ 1 spuda spuda 171 Mar 20 08:02 BaaBaaBlackSheep.txt
+ drwxrwxr-x+ 1 spuda spuda 0 Mar 20 08:11 emptydir
+ -rwxr--r--+ 1 spuda spuda 118 Mar 20 08:05 JackSprat.txt
+ drwxrwxr-x+ 1 spuda spuda 0 Mar 20 08:06 testdir1
+ drwxrwxr-x+ 1 spuda spuda 0 Mar 20 08:10 testdir2
+ drwxrwxr-x+ 1 spuda spuda 0 Mar 20 08:05 testdir3
+ ../apps/examples/cromfs/cromfs/emptydir:
+ total 0
+ ../apps/examples/cromfs/cromfs/testdir1:
+ total 2
+ -rwxr--r--+ 1 spuda spuda 249 Mar 20 08:03 DingDongDell.txt
+ -rwxr--r--+ 1 spuda spuda 247 Mar 20 08:06 SeeSawMargorieDaw.txt
+ ../apps/examples/cromfs/cromfs/testdir2:
+ total 5
+ -rwxr--r--+ 1 spuda spuda 118 Mar 20 08:04 HickoryDickoryDock.txt
+ -rwxr--r--+ 1 spuda spuda 2082 Mar 20 08:10 TheThreeLittlePigs.txt
+ ../apps/examples/cromfs/cromfs/testdir3:
+ total 1
+ -rwxr--r--+ 1 spuda spuda 138 Mar 20 08:05 JackBeNimble.txt
+
+When built into NuttX and deployed on a target, it looks like::
+
+ NuttShell (NSH) NuttX-7.24
Review Comment:
```suggestion
NuttShell (NSH) NuttX-12.3.0
##########
Documentation/components/filesystem/binfs.rst:
##########
@@ -0,0 +1,30 @@
+============
+``fs/binfs``
+============
+
+This is the binfs file system that allows "fake" execution of NSH built-
+in applications via the file system. The binfs fs file system can be
+built into the system by enabling::
+
+ CONFIG_BUILTIN=y
+ CONFIG_FS_BINFS=y
+
+It can then be mounted from the NSH command like like::
+
+ mount -t binfs /bin
+
+Example::
+
+ NuttShell (NSH) NuttX-6.31
Review Comment:
```suggestion
NuttShell (NSH) NuttX-12.3.0
##########
Documentation/components/filesystem/procfs.rst:
##########
@@ -0,0 +1,51 @@
+=============
+``fs/procfs``
+=============
+
+This is a tiny procfs file system that allows read-only access to a few
+attributes of a task or thread. This tiny procfs fs file system can be
+built into the system by enabling::
+
+ CONFIG_FS_PROCFS=y
+
+It can then be mounted from the NSH command like like::
+
+ nsh> mount -t procfs /proc
+
+Example::
+
+ NuttShell (NSH) NuttX-6.31
Review Comment:
```suggestion
NuttShell (NSH) NuttX-12.3.0
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