2020-02-15 freedom-e-sdk debug

• freedom-e21

riscv-sifive/emta-sifive/conf/machine/freedom-e21.conf

• freedom-e-sdk

scanf, getc,

1. recipe-sysroot 作用
2. gcc
   newlib？
   glibc
3. -march=ISA 如何使用

Build Configuration:                                                         
BB_VERSION           = "1.43.1"                                              
BUILD_SYS            = "x86_64-linux"                                        
NATIVELSBSTRING      = "universal-4.8"                                       
TARGET_SYS           = "riscv64-oe-linux"                                    
MACHINE              = "freedom-e21"                                         
DISTRO               = "nodistro"                                            
DISTRO_VERSION       = "nodistro.0"                                          
TUNE_FEATURES        = "riscv64 littleendian"                                
meta                 = "HEAD:6b36db836547a23f43c5f97bf3706d7b210c209c"       
meta-oe                                                                      
meta-python                                                                  
meta-multimedia                                                              
meta-networking                                                              
meta-gnome                                                                   
meta-xfce            = "HEAD:4e0538516b1e0ef42dc79bd08f7895f0052063ac"       
meta-riscv           = "HEAD:99cdf8d0cfe4b515ccac76c816091b146d0a012b"       
meta-sifive          = "HEAD:87a209be777318fefb87da6e295f4c34540717f3"       

By default, all the conversions described above are available except the floating-point conversions and the width is limited to 255 characters. The float-point conversion will be available in the extended version provided by the library libscanf_flt.a. Also in this case the width is not limited (exactly, it is limited to 65535 characters). To link a program against the extended version, use the following compiler flags in the link stage:

-Wl,-u,vfscanf -lscanf_flt -lm

A third version is available for environments that are tight on space. In addition to the restrictions of the standard one, this version implements no %[ specification. This version is provided in the library libscanf_min.a, and can be requested using the following options in the link stage:

-Wl,-u,vfscanf -lscanf_min -lm