platform_system_libufdt/ufdt_node.c, branch pie-cuttlefish-testing

Reduce call stack memory usage in ufdt_node_destruct()

2017-06-09T06:56:26+00:00

Revise the recursive function calls to be a loop in function
ufdt_node_destruct(), to reduce the call stack memory usage.

Bug: 62473375
Test: tests/run_tests.sh
Change-Id: Ifec5d655407aded115115be7d8196bfad97623d9

libufdt: reduce the number of malloc/free calling

2017-04-25T09:16:18+00:00

The performance of some bootloader malloc/free implementation isn't
optimized, but libufdt calls huge number of malloc/free to build a
real tree data structure.

The patch adds an ufdt_node_pool to reduce the number of malloc/free.
ufdt_node_pool asks a larger memory block in each time, and
distributes the memory into several ufdt_node (ufdt_node_fdt_prop
or ufdt_node_fdt_node). libufdt doesn't need to call malloc()
to allocate memory until out of larger memory block.

The setting of this patch is 1024 nodes in each memory block,
so it can reduce ~1023/1024 malloc/free calling times after the patch
is applied.

Bug: 32969430
Test: ./tests/run_tests.sh
Test: ./tests/run_performance_test.sh
Change-Id: Id95e74da1235b9e2fc306500686515ee6b93017d

Correct code placement for different license

2017-04-17T02:31:11+00:00

Previous code revising moved some code into a file with different license.
Fix it in this patch.

Test: ./tests/run_tests.sh
Change-Id: Ie50000bba7a6bf8d9d65dcc1a1cf21135ac3b97a

Code revise

2017-04-15T03:09:17+00:00

- Remove unused code
- Remove internel functions from header file
- Fix typos
- Revise all function names with prefix ufdt_*

Test: ./tests/run_tests.sh
Change-Id: I4f89e90eb983540e78aadb092c07de62d219e454

Add Apache2 module license

2017-04-15T02:49:05+00:00

Bug: 36678371
Test: mmm system/libufdt, and success build
Change-Id: I73059f5beca2242f8883fca86cb49d53d0f543b8

Avoid to re-generate string table from ufdt to fdt

2017-04-13T07:28:55+00:00

String table contains the strings of all property name in a fdt.

The ufdt_apply_overlay() converts two dtbs from fdt to ufdt,
overlays, and converts merged ufdt to fdt. These operations
shouldn't create new peroperty names, so we can just re-use the
string tables in original dtbs, and just copy them into merged
fdt. This solution can enhance a lot of performance for device
tree overlaying.

To avoid the error that some users could use string offset in
string table, the solution also give a same string offset for
the name properties by ufdt_prop_dict;

Futher, the patch also removed unused header files after
changing algorithm.

Bug: 35255584
Test: ./tests/run_tests.sh
Change-Id: Id422730115531bd20d21117285291bdd860915ff

Fix the libufdt overlay node order

2017-02-21T03:42:14+00:00

libufdt could reversed the node order during overlaying.

However, the libfdt overlay in dtc doesn't promise the node order.
But looks there are some implementation of kernel drivers depend on
the order in DTS.

The patch keeps the DTB/DTBO node order during libufdt overlaying.
Notes that the node order merged by libufdt could not match the
result of libfdt.

Bug: 35429321
Test: run test scripts (see libufdt/tests/README)
Change-Id: I7209ebfaa21d6640d547b029ea0f0edf6e58fca1

libufdt: device tree overlay via unflattening FDT

2016-12-21T04:25:33+00:00

The original version of libdtoverlay is slow in searching for
particular nodes and adding subnodes/properties due to the operations
on flattened device tree (FDT).

`libufdt` builds a real tree structure (named ufdt -- unflattned
device tree) from FDT. In the real tree, we can perform certain
operations (e.g., merge 2 subtrees, search for a node by path) in
almost optimal time complexity with acceptable additional memory usage.

With libufdt, we improve the merging of two dtb files from O(N^2) to
O(N), where N is the number of nodes in the tree.

Bug: 30800619
Test: run test scripts (see libufdt/tests/README)
Test: manually ported libufdt into a bootloader,
      checked it can merge a base dtb and a dtbo to generate a final dtb
      to boot the device

Change-Id: I1ff886bb8a62bad1451edcd7c4fe5cb48b7a034a

Revert "libufdt: device tree overlay via unflattening FDT"

2016-12-14T02:36:07+00:00

This reverts commit 3084ce7cbdff84093286459758f99c15082e6556.

Change-Id: I36f8252ea77c75301711009180c1908bb18e231c

libufdt: device tree overlay via unflattening FDT

2016-12-05T23:30:16+00:00

The original version of libdtoverlay is slow in searching for
particular nodes and adding subnodes/properties due to the operations
on flattened device tree (FDT).

`libufdt` builds a real tree structure (named ufdt -- unflattned
device tree) from FDT. In the real tree, we can perform certain
operations (e.g., merge 2 subtrees, search for a node by path) in
almost optimal time complexity with acceptable additional memory usage.

With libufdt, we improve the merging of two dtb files from O(N^2) to
O(N), where N is the number of nodes in the tree.

Bug: 30800619
Test: run test scripts (see libufdt/tests/README)
Test: manually ported libufdt into a bootloader,
      checked it can merge a base dtb and a dtbo to generate a final dtb
      to boot the device
Change-Id: I6a282cc99129d5280ecbf40852723f83735fa523