调整busybox中syslogd读取内核printk信息长度

busybox 默认读取内核printk信息长度256, 通过CONFIG_FEATURE_SYSLOGD_READ_BUFFER_SIZE宏可调整, 如下:

#cd busybox-1.21.1
#make menuconfig
找到:
System Logging Utilities  --->
[*] syslogd
  [*]   Rotate message files
  [*]   Remote Log support
  [*]   Support -D (drop dups) option
  [*]   Support syslog.conf
  (4096) Read buffer size in bytes