diff --git a/.travis.yml b/.travis.yml
index 63c2356..3f76a7c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -14,25 +14,27 @@ os:
 
 env:
   matrix:
-    - ARCH="riscv32"
-    - ARCH="riscv64"
-    - ARCH="i386"
-#    - ARCH="x86_64"
-    - ARCH="aarch64"
+    - ARCH="riscv32" SRC="ucore"
+    - ARCH="riscv64" SRC="ucore"
+    - ARCH="i386" SRC="ucore"
+#    - ARCH="x86_64" SRC="ucore"
+    - ARCH="aarch64" SRC="ucore"
+    - ARCH="x86_64" SRC="biscuit"
 
 install:
   - if [ $ARCH = riscv32 ] || [ $ARCH = riscv64 ]; then
-    [ $TRAVIS_OS_NAME = linux ] && export FILE="riscv64-unknown-elf-gcc-8.1.0-2018.12.0-x86_64-linux-ubuntu14";
-    [ $TRAVIS_OS_NAME = osx   ] && export FILE="riscv64-unknown-elf-gcc-8.1.0-2018.12.0-x86_64-apple-darwin";
+    [ $TRAVIS_OS_NAME = linux ] && export FILE="riscv64-unknown-elf-gcc-8.1.0-2019.01.0-x86_64-linux-ubuntu14";
+    [ $TRAVIS_OS_NAME = osx   ] && export FILE="riscv64-unknown-elf-gcc-8.1.0-2019.01.0-x86_64-apple-darwin";
     wget https://static.dev.sifive.com/dev-tools/$FILE.tar.gz;
     tar xf $FILE.tar.gz;
     export PATH=$PATH:$PWD/$FILE/bin;
     fi
   - if [ $ARCH = aarch64 ]; then
     if [ $TRAVIS_OS_NAME = linux ]; then
-    wget https://web.stanford.edu/class/cs140e/files/aarch64-none-elf-linux-x64.tar.gz;
-    tar -xzvf aarch64-none-elf-linux-x64.tar.gz;
-    export PATH=$PATH:$PWD/aarch64-none-elf/bin;
+    export FILE="gcc-arm-8.2-2018.11-x86_64-aarch64-elf";
+    wget https://developer.arm.com/-/media/Files/downloads/gnu-a/8.2-2018.11/$FILE.tar.xz;
+    tar -xvf $FILE.tar.xz;
+    export PATH=$PATH:$PWD/$FILE/bin;
     elif [ $TRAVIS_OS_NAME = osx ]; then
     brew tap SergioBenitez/osxct;
     brew install aarch64-none-elf;
@@ -51,7 +53,7 @@ install:
     fi
 
 script:
-  - cd ucore
+  - cd $SRC
   - mkdir build && cd build
   - cmake -DARCH=$ARCH ..
   - make
diff --git a/README.md b/README.md
index ea2668a..7d5ae17 100644
--- a/README.md
+++ b/README.md
@@ -1,10 +1,37 @@
-# User programs from ucore_os_lab in C-lang
+# rCore-user
 
 [![Build Status](https://travis-ci.org/wangrunji0408/rcore_user.svg?branch=master)](https://travis-ci.org/wangrunji0408/rcore_user)
 
+User programs for [rCore OS](https://github.com/wangrunji0408/RustOS).
+
+
+
+Now it has 2 parts:
+
+* `ucore`: C-lang, from the original [ucore_os_lab](https://github.com/chyyuu/ucore_os_plus)
+* `biscuit`: C/C++, from [Biscuit](https://github.com/mit-pdos/biscuit), based on a partial libc `litc`. (WIP)
+
 ## Build
+
+For ucore:
+
 ```bash
+cd ucore
 mkdir build && cd build
 cmake -DARCH={i386,x86_64,riscv32,riscv64,aarch64} ..
 make
-```
\ No newline at end of file
+```
+
+For biscuit:
+
+```bash
+cd biscuit
+mkdir build && cd build
+cmake -DARCH=x86_64 ..
+make
+```
+
+## Notice
+
+* The syscall ids have been set compatible with Linux64.
+* So the ucore part can not run on the original ucore.
\ No newline at end of file
diff --git a/ucore/CMakeLists.txt b/ucore/CMakeLists.txt
index 78d87f2..ee594b1 100644
--- a/ucore/CMakeLists.txt
+++ b/ucore/CMakeLists.txt
@@ -34,7 +34,11 @@ elseif (${ARCH} STREQUAL riscv64)
     set(PREFIX              riscv64-unknown-elf-)
     set(CMAKE_C_FLAGS       "-march=rv64imac -mabi=lp64 -mcmodel=medany")
 elseif (${ARCH} STREQUAL aarch64)
-    set(PREFIX              aarch64-none-elf-)
+    if(APPLE)
+        set(PREFIX          aarch64-none-elf-)
+    else()
+        set(PREFIX          aarch64-elf-)
+    endif ()
     set(CMAKE_C_FLAGS       "-mgeneral-regs-only")
     set(LINK_FLAGS          "-Ttext 0xffff000000000000")
 else()