I found the startup.S function that difference between the MPC5748G demos : flexcan_receive(...:\flexcan_receive\flexcan_receive_Z4_0\Project_Settings\Startup_Code),
Here the pictures are below:
1.flexcan_receive : e_b __dcache_cfg in the __dcache_inv
2. linflexd_uart : e_b __icache_cfg in the __dcache_inv
Now I uesd flexcan_receive example in my project, and we needed to integrate uart(channel 2) receive module. linflexd_uart example can receive the correct char which we need, but in my project uart ch2 always received '0'. I contrasted these examples,and found there is differece betwwen them in Startup_Code. I copyed the
linflexd_uart\linflexd_uart_Z4_1\Project_Settings\Startup_Code \ startup.S to flexcan_receive\flexcan_receive_Z4_0\Project_Settings\Startup_Code\ startup.S .At last uart ch2 can receive the correct char which we need.