Android中/system/build.prop文件解讀 @ TN-Man's 組合屋

原作者不知道是誰orz

在/system下的build.prop文件裡，我們常看見以下語句。
ro.ril.hsdpa.category = 10
ro.ril.hsupa.category = 6
ro.ril.hsxpa = 2
ro.ril.enable.amr.wideband=1
wifi.supplicant_scan_interval=45
dalvik.vm.heapsize=24m //OutOfMemoryError
ro.ril.def.agps.mode = 2
這幾行主要是設置網絡數據、定位、語音、內存等方面的優化。

======================================================
根據上面的參數代碼，下面列出不同數值對應代表的意義
ro.ril.hsdpa.category :
1 = 1.2 Mbit/s
2 = 1.2 Mbit/s
3 = 1.8 Mbit/s
4 = 1.8 Mbit/s
5 = 3.6 Mbit/s
6 = 3.6 Mbit/s
7 = 7.2 Mbit/s
8 = 7.2 Mbit/s
9 = 10.1 Mbit/s
10 = 14.0 Mbit/s
11 = 0.9 Mbit/s
12 = 1.8 Mbit/s
13 = 17.6 Mbit/s
14 = 21.1 Mbit/s
15 = 23.4 Mbit/s
16 = 27.9 Mbit/s
19 = 35.3 Mbit/s
20 = 42.2 Mbit/s
21 = 23.4 Mbit/s
22 = 27.9 Mbit/s
23 = 35.3 Mbit/s
24 = 42.2 Mbit/s
25 = 46.8 Mbit/s
26 = 55.9 Mbit/s
27 = 70.6 Mbit/s
28 = 84.4 Mbit/s
HSDPA（High Speed Downlink Packet Access)：高速下行分組接入

ro.ril.hsupa.category :
1 = 0.73 Mbit/s
2 = 1.46 Mbit/s
3 = 1.46 Mbit/s
4 = 2.93 Mbit/s
5 = 2.00 Mbit/s
6 = 5.76 Mbit/s
7 = 11.5 Mbit/s
HSUPA (high speed uplink packet access)：高速上行鏈路分組接入

ro.ril.hsxpa : 3G數據標準選擇
0 – UMTS r99
1 – HSDPA
2 – HSDPA/HSUPA

ro.ril.enable.amr.wideband：
0 – 關閉對AMR wideband /HD Audio的支持
1 – 打開對AMR wideband /HD Audio的支持
AMR WideBand，語音帶寬範圍，全稱為「Adaptive Multi-rate - Wideband」，即「自適應多速率寬帶編碼」，
採樣頻率為16kHz，是一種同時被國際標準化組織 ITU-T和3GPP採用的寬帶語音編碼標準，也稱為G722.2標準。
AMR-WB提供語音帶寬範圍達到50～7000Hz，用戶可主觀感受到話音比以前更加自然、舒適和易於分辨。
AMR-WB應用於EDGE、3G可充分體現其優勢。足夠的傳輸帶寬保證AMR-WB可採用從6.6kb/s到23.85kb/s共九種編碼，語音質量超越PSTN固定電話。
PS：這裡需要注意的是有些版本的Radio不支持AMR wideband，那樣就算設置為1也支持不了這功能。

wifi.supplicant_scan_interval:
wifi無線局域網掃瞄間隔時間，單位為秒。
調大這個值可節約耗電。

dalvik.vm.heapsize=24m：
虛擬內存大小，單位為Mb,調大這個可以略微提高性能，對於某些FC問題確實有用。
在hdpi下，不設置成24m以上，就會導致系統無法啟動。

ro.ril.def.agps.mode：AGPS模式選擇
0 – 關閉AGPS服務支持。可以節約耗電和網絡流量，不過會延長GPS定位時間。
1 –
2 – 打開AGPS服務支持。

wanqi@wanqi-System-Product-Name:~/huiye_Q9/msm7627-app$
wanqi@wanqi-System-Product-Name:~/huiye_Q9/msm7627-app$ adb push build.prop /system/
52 KB/s (2362 bytes in 0.044s)
wanqi@wanqi-System-Product-Name:~/huiye_Q9/msm7627-app$ adb shell getprop | grep heap
[dalvik.vm.heapsize]: [24m]
wanqi@wanqi-System-Product-Name:~/huiye_Q9/msm7627-app$ adb shell getprop | grep heap
[dalvik.vm.heapsize]: [48m]
wanqi@wanqi-System-Product-Name:~/huiye_Q9/msm7627-app$ adb shell getprop | grep heap
[dalvik.vm.heapsize]: [48m]
wanqi@wanqi-System-Product-Name:~/huiye_Q9/msm7627-app$ adb pull /system/build.prop .
29 KB/s (2362 bytes in 0.078s)
wanqi@wanqi-System-Product-Name:~/huiye_Q9/msm7627-app$ vim build.prop
wanqi@wanqi-System-Product-Name:~/huiye_Q9/msm7627-app$ adb push build.prop /system/
50 KB/s (2362 bytes in 0.045s)
wanqi@wanqi-System-Product-Name:~/huiye_Q9/msm7627-app$ adb shell getprop | grep heap
[dalvik.vm.heapsize]: [48m]
wanqi@wanqi-System-Product-Name:~/huiye_Q9/msm7627-app$

開機初始化會在對應的init.rc中增加如下一行：setprop dalvik.vm.heapsize 48m。

ActivityManager.java (android/frameworks/base/core/java/android/app): String vmHeapSize = SystemProperties.get("dalvik.vm.heapsize", "16m");
AndroidRuntime.cpp (android/frameworks/base/core/jni): property_get("dalvik.vm.heapsize", heapsizeOptsBuf+4, "16m");
Init.pxa910-based.rc (android/vendor/omap/tw50f/rootdir): setprop dalvik.vm.heapsize 32m
Init.pxa910-based.rc (android/vendor/omap/tw60f/rootdir): setprop dalvik.vm.heapsize 32m
Main.c (android/external/qemu/android): boot_property_add("dalvik.vm.heapsize",tmp);

build.prop 是一個屬性文件，在Android系統中.prop文件很重要，記錄了系統的設置和改變，類似於/etc中的文件。

# begin build properties
# autogenerated by buildinfo.sh
ro.build.id=GRI40
ro.build.display.id=GRJ22
ro.build.version.incremental=eng.mur4ik.20110505.195322
ro.build.version.sdk=10 2.3ROM
ro.build.version.codename=REL
ro.build.version.release=2.3.4 android版本
ro.build.date=三 12月 15 20:41:26 CST 2010 時區時間CST可以代表4個時區，這個百度一下
ro.build.date.utc=0
ro.build.type=user
ro.build.user=mur4ik
ro.build.host=mur4ik-VirtualBox
ro.build.tags=test-keys
ro.product.model=GT540 手機型號
ro.product.brand=google
ro.product.name=swift
ro.product.device=swift
ro.product.board=swift
ro.product.cpu.abi=armeabi-v6l
ro.product.cpu.abi2=armeabi
ro.product.manufacturer=LGE
ro.product.locale.language=zh 刷機後默認語言
ro.product.locale.region=CN 刷機後啟動的默認語言
ro.board.platform=msm7k
# ro.build.product is obsolete; use ro.product.device
ro.build.product=swift
# Do not try to parse ro.build.description or .fingerprint
ro.build.description=soju-user 2.3.3 GRI40 102588 release-keys 內部版本號
ro.build.fingerprint=google/soju/crespo:2.3.3/GRI40/102588:user/release-keys
# end build properties

#
# system.prop for optimus
#

###RIL Config

rild.libpath=/system/lib/libril-qc-1.so
rild.libargs=-d /dev/smd0
persist.rild.nitz_plmn=
persist.rild.nitz_long_ons_0=
persist.rild.nitz_long_ons_1=
persist.rild.nitz_long_ons_2=
persist.rild.nitz_long_ons_3=
persist.rild.nitz_short_ons_0=
persist.rild.nitz_short_ons_1=
persist.rild.nitz_short_ons_2=
persist.rild.nitz_short_ons_3=
DEVICE_PROVISIONED=1

# LGE_CHANGE_S, [jeongmini.park@lge.com], 2010-05-03, < Enabed EONS feature >
persist.cust.tel.eons=1
# LGE_CHANGE_E, [jeongmini.park@lge.com], 2010-05-03, < Enabed EONS feature >

## QC RIL doesn't replay call rings
ro.telephony.call_ring.multiple=false
ro.telephony.call_ring.delay=3000 響鈴延遲，單位為毫秒。（怪盜補充）

# Default network type. 默認網絡類型
# 0 => WCDMA preferred.
ro.telephony.default_network=0
ro.ril.baseband=AMSS53404003
ro.ril.ecclist=112,911,101,102,103
ro.ril.gprsclass=12
ro.ril.hsxpa=2 3G數據標準選擇 0 – UMTS r99 1 – HSDPA 2 – HSDPA/HSUPA

# Touch Key, hopemini@lge.com, 2009-12-10
# SEARCH, BACK, HOME, MENU, CALL, END
ro.lge.touchkey=MENU|BACK
# Vibrator amp default value
ro.lge.vibrator_amp=125

## wifi
wifi.interface=wlan0
wifi.supplicant_scan_interval=120 WIFI掃瞄時間單位為秒調大這個值可節約耗電
ro.wifi.channels=14

## opengles 2.0 LINUX下針對多媒體的一些功能
ro.opengles.version=131072
# Uncomment below to enable using MDP for composition
# Change to 1 for enable using GPU for composition
debug.sf.hw=1 硬件加速設定 0是關閉, 1是開啟
video.accelerate.hw=1

ro.media.dec.aud.wma.enabled=1
ro.media.dec.vid.wmv.enabled=1
ro.media.dec.aud.flac.enabled=1
ro.media.dec.aud.ape.enabled=1
ro.media.dec.vid.avi.enabled=1
ro.media.dec.vid.flv.enabled=1
ro.media.dec.vid.qt.enabled=1
ro.media.dec.vid.rm.enabled=1

media.stagefright.enable-player=true
media.stagefright.enable-meta=false
media.stagefright.enable-scan=false
media.stagefright.enable-http=false

ro.config.sync=yes

#increase dalvik heap size, yongchan.jeong@lge.com, 20100719
dalvik.vm.dexopt-flags=m=y
dalvik.vm.heapsize=24m 虛擬內存範圍由12M-48M, 默認是24M
dalvik.vm.execution-mode=int:jit
dalvik.vm.lockprof.threshold=500
windowsmsg.max_events_per_sec=260

persist.service.mount.playsnd=0
ro.com.google.locationfeatures=1
ro.setupwizard.enable_bypass=1

## BEGIN: yongmin.jung@lge.com 2010-05-18
## ADD : set lcd density to 160
ro.sf.lcd_density=160 DPI
ro.sf.hw_lcd_density=160
## END: yongmin.jung@lge.com 2010-05-18

#
# ADDITIONAL_BUILD_PROPERTIES
#
keyguard.no_require_sim=true
ro.product.model=LG-GT540
ro.rommanager.developerid=cyanogenmod
ro.url.legal=http://www.google.com/intl/%s/mobile/android/basic/phone-legal.html
ro.url.legal.android_privacy=http://www.google.com/intl/%s/mobile/android/basic/privacy.html
ro.com.google.clientidbase=android-google
ro.com.android.wifi-watchlist=GoogleGuest
ro.setupwizard.enterprise_mode=1
ro.com.android.dateformat=MM-dd-yyyy
ro.com.android.dataroaming=false
ro.config.ringtone=Playa.ogg 默認來電鈴聲
ro.config.notification_sound=regulus.ogg 默認通知鈴聲
ro.config.alarm_alert=Alarm_Beep_03.ogg 默認鬧鐘鈴聲
ro.modversion=CyanogenMod-7.0.3-GT540-MUR4IK MOD版本號
ro.setupwizard.mode=DISABLED 開機出現的帳號設置嚮導，ENABLED為顯示，DISABLED為禁用，OPTIONAL為可選
net.bt.name=Android
dalvik.vm.stack-trace-file=/data/anr/traces.txt