[fix] 更新BSP配置

Author: MuChenger

bsp/xuantie/smartl/e901/README.md

@@ -87,6 +87,12 @@ E901+ 处理器体系结构的主要特点如下：
 
 <img src="figures/2.scons.png" alt="env" style="zoom: 95%;" />
 
+如果期望进一步减小固件的大小，添加下述编译参数使用minilibc库可以有效降低固件大小。
+
+```
+-specs=minilibc.specs
+```
+
 生成可执行文件，可以直接在命令行启动qemu或者配置vscode脚本借助vscode强大的插件进行图形化调试，qemu的相关命令可以查看玄铁qemu的[用户手册](https://www.xrvm.cn/community/download?id=4397435198627713024)，下述是启动qemu的命令，在powershell或命令行可直接执行下述命令，注意qemu需要导出至环境变量或者使用绝对路径。
 
 ```shell

bsp/xuantie/smartl/e901/rtconfig.py

@@ -64,16 +64,16 @@
                       )
 
     CFLAGS = DEVICE + ' -g -Wall -Wno-unused-function -Wformat -Wformat-security -Warray-bounds -Wuninitialized \
-                        -Wreturn-type -Wcomment -Wswitch -Wparentheses -specs=minilibc.specs -MP -MMD -Os -Wpointer-arith \
+                        -Wreturn-type -Wcomment -Wswitch -Wparentheses -MP -MMD -Os -Wpointer-arith \
                         -Wno-undef -ffunction-sections -fdata-sections -fno-inline-functions -fno-builtin \
                         -fno-strict-aliasing -Wno-char-subscripts -Wno-unused-but-set-variable ' + GLOBAL_DEFINES
 
     AFLAGS = DEVICE + ' -g -Wall -Wno-unused-function -Wformat -Wformat-security -Warray-bounds -Wuninitialized \
-                        -Wreturn-type -Wcomment -Wswitch -Wparentheses -specs=minilibc.specs -MP -MMD -Os -Wpointer-arith \
+                        -Wreturn-type -Wcomment -Wswitch -Wparentheses  -MP -MMD -Os -Wpointer-arith \
                         -Wno-undef -ffunction-sections -fdata-sections -fno-inline-functions -fno-builtin \
                         -fno-strict-aliasing -Wno-char-subscripts -Wno-unused-but-set-variable ' + ' -MP -MMD -D"Default_IRQHandler=SW_handler" ' + GLOBAL_DEFINES
 
-    LFLAGS = DEVICE +  ' -MP -MMD  -Wl,-zmax-page-size=1024 -Wl,-Map=yoc.map -Wl,-zmax-page-size=1024 -Wl,-Map=yoc.map -Wl,--whole-archive -Wl,--no-whole-archive -specs=minilibc.specs -nostartfiles -Wl,--gc-sections '
+    LFLAGS = DEVICE +  ' -MP -MMD  -Wl,-zmax-page-size=1024 -Wl,-Map=yoc.map -Wl,-zmax-page-size=1024 -Wl,-Map=yoc.map -Wl,--whole-archive -Wl,--no-whole-archive  -nostartfiles -Wl,--gc-sections '
     LFLAGS += ' -T ' + LINK_FILE
 
     CPATH = ''