device: optimize handles array (b5c4140a) · Commits · Wenxi XU / zephyr

Optimize the handles array by making the following observations: * The devicetree ordinal at index 0 in pass1 is discarded by gen_handles.py, and therefore does not appear in the pass2 array. * gen_handles.py does not need `DEVICE_HANDLE_ENDS` to determine the end of the handle array, as that information is present in the .elf. Therefore, instead of replacing the devicetree ordinal with an additional `DEVICE_HANDLE_ENDS` at the end (to preserve lengths), we can simply move the ordinal to the end and have it be the original `DEVICE_HANDLE_ENDS` symbol. This reduces the size of the array by one handle per device (2 bytes). Signed-off-by:

Jordan Yates <jordan.yates@data61.csiro.au>

include/device.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -702,7 +702,6 @@ BUILD_ASSERT(sizeof(device_handle_t) == 2, "fix the linker scripts");
		)) \
		DEVICE_HANDLE_SEP, \
		Z_DEVICE_EXTRA_HANDLES(__VA_ARGS__) \
		DEVICE_HANDLE_ENDS, \
		};

		#define Z_DEVICE_DEFINE_INIT(node_id, dev_name, pm_control_fn) \

scripts/gen_handles.py

+5 −3

Original line number	Diff line number	Diff line
		@@ -241,7 +241,7 @@ def main():
		handle.dev_deps = []
		handle.ext_deps = []
		deps = handle.dev_deps
		while True:
		while hvi < len(hv):
		h = hv[hvi]
		if h == DEVICE_HANDLE_ENDS:
		break
		@@ -303,7 +303,9 @@ def main():
		# When CONFIG_USERSPACE is enabled the pre-built elf is
		# also used to get hashes that identify kernel objects by
		# address. We can't allow the size of any object in the
		# final elf to change.
		# final elf to change. We also must make sure at least one
		# DEVICE_HANDLE_ENDS is inserted.
		assert len(hdls) < len(hs.handles), "%s no DEVICE_HANDLE_ENDS inserted" % (dev.sym.name,)
		while len(hdls) < len(hs.handles):
		hdls.append(DEVICE_HANDLE_ENDS)
		assert len(hdls) == len(hs.handles), "%s handle overflow" % (dev.sym.name,)

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