Android How to write to / proc / cmdline in the kernel bootparameter

Now you want to set bootlader version number, found in the main setting in init.c
property_set ("ro.serialno", serialno [0]? serialno: "");
property_set ("ro.bootmode", bootmode [0]? bootmode: "unknown");
property_set ("ro.baseband", baseband [0]? baseband: "unknown");
property_set ("ro.carrier", carrier [0]? carrier: "unknown");
And here's the bootmode [0] is from / proc / cmdline read out , cat cmdline only for a moment
mem = 212M console = ttyMSM2, 115200n8 androidboot.hardware = qcom appsbl.Ver = 1.1
So ro.boot set became unknown.
not find the / proc / cmdline in the writing process , I do not know how to write the content ?
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I remember like linux_banner which is to set the content , you see, a little forgotten.
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should be configured in BoardConfig.mk :
BOARD_KERNEL_CMDLINE: = mem = 212M console = ttyMSM2, 115200n8 console = ttyHSL1, 115200n8 androidboot.hardware = qcom
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grace . QCOM platform is configured in BoardConfig.mk inside , MTK 's no variable assignment , needs its own configuration.