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[wifi] Avoid .rodata RAM cost for ManualIP on ESP8266

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On ESP8266, .rodata is mapped to DRAM (RAM), not flash. When
StructInitializer is used with all compile-time constant fields,
the compiler places the entire struct as a const blob in .rodata,
silently consuming ~20 bytes of RAM.

Switch to field-by-field assignment on ESP8266 so the IP address
values are encoded as immediate operands in flash instructions
instead of a .rodata blob. Other platforms continue to use the
aggregate initializer since their .rodata is flash-mapped.
This commit is contained in:
J. Nick Koston
2026-02-23 16:06:28 -06:00
parent 4a52900352
commit abcd89cd1f
2 changed files with 23 additions and 5 deletions
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22
esphome/components/wifi/__init__.py
View File

@@ -439,13 +439,25 @@ def safe_ip(ip):
def manual_ip(config):
if config is None:
return None
fields = {
"static_ip": CONF_STATIC_IP,
"gateway": CONF_GATEWAY,
"subnet": CONF_SUBNET,
"dns1": CONF_DNS1,
"dns2": CONF_DNS2,
}
if CORE.is_esp8266:
# On ESP8266, .rodata is mapped to RAM. Using StructInitializer with all
# compile-time constant fields causes the compiler to place a const blob
# in .rodata, silently consuming ~20 bytes of RAM. Field-by-field assignment
# encodes the values as immediate operands in flash instructions instead.
cg.add(cg.RawExpression("wifi::ManualIP manual_ip{}"))
for member, key in fields.items():
cg.add(cg.RawExpression(f"manual_ip.{member} = {safe_ip(config.get(key))}"))
return cg.RawExpression("manual_ip")
return cg.StructInitializer(
ManualIP,
("static_ip", safe_ip(config[CONF_STATIC_IP])),
("gateway", safe_ip(config[CONF_GATEWAY])),
("subnet", safe_ip(config[CONF_SUBNET])),
("dns1", safe_ip(config.get(CONF_DNS1))),
("dns2", safe_ip(config.get(CONF_DNS2))),
*((member, safe_ip(config.get(key))) for member, key in fields.items()),
)

6
tests/components/wifi/test.esp8266-ard.yaml
View File

@@ -1,6 +1,12 @@
wifi:
min_auth_mode: WPA2
post_connect_roaming: true
manual_ip:
static_ip: 192.168.1.100
gateway: 192.168.1.1
subnet: 255.255.255.0
dns1: 1.1.1.1
dns2: 8.8.8.8
packages:
- !include common.yaml