Description:[feature] support customized hilog ring buffer size

Change-Id: I5d23deaada5939bbb6fb57505f72c2348bd6afe9
Signed-off-by: Nshenchenkai <shenchenkai@huawei.com>

kernel/extended/Kconfig

@@ -102,3 +102,6 @@ source "kernel/extended/perf/Kconfig"
 
 ######################### config options of lms #########################
 source "kernel/extended/lms/Kconfig"
+
+######################### config options of hilog #########################
+source "kernel/extended/hilog/Kconfig"
\ No newline at end of file

kernel/extended/hilog/Kconfig

+config HILOG
+    tristate "Hilog support"
+    default y
+    help
+      hilog buffer manager.
+
+      Hilog is a simple log manager for OpenHarmonyOS.
+      log string write to /dev/hilog, and the hilog driver copy it
+      to the ring buffer. Ring buffer can be read from userspace.
+
+config HILOG_BUFFER_SIZE
+    int "hilog buffer size"
+    default 4096
+    help
+      Define the default ring buffer size of hilog
\ No newline at end of file

kernel/extended/hilog/los_hilog.c

@@ -41,7 +41,7 @@
 #include "los_vm_lock.h"
 #include "user_copy.h"
 
-#define HILOG_BUFFER 4096
+#define HILOG_BUFFER LOSCFG_HILOG_BUFFER_SIZE
 #define DRIVER_MODE 0666
 #define HILOG_DRIVER "/dev/hilog"
 
@@ -255,6 +255,7 @@ static void HiLogCoverOldLog(size_t bufLen)
     int retval;
     struct HiLogEntry header;
     size_t totalSize = bufLen + sizeof(struct HiLogEntry);
+    int dropLogLines = 0;
 
     while (totalSize + g_hiLogDev.size > HILOG_BUFFER) {
         retval = HiLogReadRingBuffer((unsigned char *)&header, sizeof(header));
@@ -262,9 +263,13 @@ static void HiLogCoverOldLog(size_t bufLen)
             break;
         }
 
+        dropLogLines++;
         HiLogBufferDec(sizeof(header));
         HiLogBufferDec(header.len);
     }
+    if (dropLogLines > 0) {
+        dprintf("hilog ringbuffer full, drop %d line(s) log", dropLogLines);
+    }
 }
 
 int HiLogWriteInternal(const char *buffer, size_t bufLen)