Cyclone 5 first boot linux crashes, howto debug?

Hello,

here is more information

the device tree:

#include "socfpga_cyclone5.dtsi"
/ {
    model = "Model";
    compatible = "altr,socfpga-cyclone5", "altr,socfpga";
    chosen {
        bootargs = "earlyprintk";
        stdout-path = "serial0:115200n8";
    };
    memory@0{
        name = "memory";
        device_type = "memory";
        reg = <0x0 0x40000000>; /* 1GB */
    };
    aliases {
        /* this allow the ethaddr uboot environmnet variable contents
         * to be added to the gmac1 device tree blob.
         */
        ethernet0 = &gmac1;
	rtc0 = &mcp_rtc;
    };
    regulator_3_3v: vcc3p3-regulator {
        compatible = "regulator-fixed";
        regulator-name = "VCC3P3";
        regulator-min-microvolt = <3300000>;
        regulator-max-microvolt = <3300000>;
    };
    fpga_bridge3: fpga-bridge@ffc25080 {
        compatible = "altr,socfpga-fpga2sdram-bridge";
	reg = <0xffc25080 0x4>;
    };
    msgdma_wr: msgdma_wr@0xff204000 {
	compatible = "msgdma_wr";
	reg = <0xff204000 0x40>;
	interrupt-parent = <&intc>;
	interrupts = <0 40 4>;
    };
	msgdma_rd: msgdma_rd@0xff204040 {
	compatible = "msgdma_rd";
	reg = <0xff204040 0x40>;
	interrupt-parent = <&intc>;
	interrupts = <0 41 4>;
    };
};
&gmac1 {
	status = "okay";
	phy-mode = "rgmii";
  /* 0 bis 900*/
	rxd0-skew-ps = <420>;
	rxd1-skew-ps = <420>;
	rxd2-skew-ps = <420>;
	rxd3-skew-ps = <420>;
	rxdv-skew-ps = <420>;

	txd0-skew-ps = <360>;
	txd1-skew-ps = <360>;
	txd2-skew-ps = <360>;
	txd3-skew-ps = <360>;
	txen-skew-ps = <360>;
/* 0 bis 1860*/
	rxc-skew-ps = <1680>;
	txc-skew-ps = <1740>;

	max-frame-size = <3800>;
};

&i2c0 {
	status = "okay";
	speed-mode = <0>;

	i2c-switch@70 {
		compatible = "nxp,pca9548";
		#address-cells = <1>;
		#size-cells = <0>;
		reg = <0x70>;

		i2c@1{
			#address-cells = <1>;
			#size-cells = <0>;
			reg = <1>;

			mcp_rtc: rtc@6f{
         			compatible = "microchip,mcp7941x";
				reg = <0x6F>;
			};
		};
	};
};

&i2c1 {
    status = "okay";
    speed-mode = <0>;
    gpioexp@20 {
        compatible = "ti,tca6416";
        reg = <0x20>;
    };
    e2prom@50 {
        compatible = "at,24c01";
        reg = <0x50>;
    };
    tempsens@48 {
        compatible = "ti,tmp108";
        reg = <0x48>;
	status = "okay";
    };
};

&mmc0 {
    vmmc-supply = <&regulator_3_3v>;
    vqmmc-supply = <&regulator_3_3v>;
    status = "okay";
};
&usb1 {
    status = "okay";
};
&gpio0 {
    status = "okay";
};
&gpio1 {
    status = "okay";
};
&gpio2 {
    status = "okay";
};

the overlay file:

/dts-v1/;
/plugin/;
/ {
	fragment@0 {
		target-path = "/soc/base-fpga-region";
		__overlay__ {
			firmware-name = "socfpga.rbf";
			fpga-bridges = <&fpga_bridge0>, <&fpga_bridge1>, <&fpga_bridge3>;
		};
	};
};

the firmware is written at runtime.

I modified some code for publication purposes (not tested for compilation):

std::string fpga::write_firmware(void)
{
	std::string msg;
	char *dir = nullptr;
	char *dir_ch = nullptr;

	m_firmware_ok = false;

	dir_ch = strdup("/sys/kernel/config/device-tree/overlays/m3/path");
	if(dir_ch == nullptr)
		msg ="Can not malloc memory for /sys/kernel/config/device-tree/overlays/m3/path";

	if(msg.empty() == true)
	{
		dir = dirname(dir_ch);
		if(dir == nullptr)
			msg = "Can not malloc memory for dirname";
	}

	if(msg.empty() == true)
	{
		if(set_enable(false).is_error())
			msg = "Enable not switched off";
	}

	if(msg.empty() == true)
	{
		if(chdir(dir) == 0)
		{
			if(rmdir(dir) != 0)
				msg = "Could not delete sysfs";
		}
	}

	if(msg.empty() == true)
	{
		if(mkdir(dir, S_IRWXU) != 0)
			msg = "Could not create sysfs";
	}

	if(msg.empty() == true)
	{
		std::ofstream wpd("/sys/kernel/config/device-tree/overlays/m3/path");
		wpd << socfpga_overlay.dtb";
		wpd.close();
		if(wpd.fail())
		{
			msg = "Could not open fpga fw errno: " + std::to_string(errno);
		}
	}

	if(msg.is_no_error())
	{
		WORD timeout = 0;

		bool finished_bridge = false;
		bool finished_manager = false;

		do
		{
			if(!(finished_bridge && finished_manager))
				ica::chrono::sleep_for(std::chrono::milliseconds(3000));

			finished_bridge = get_bridge_state();
			finished_manager = get_fpga_manager_state();

			timeout++;
		}while(timeout < ica::fpga::timeout_bridge_restart && !(finished_bridge && finished_manager));

		if(timeout == 10)
			msg = "FPGA bridge or manager not okay";
	}

	if(msg.empty() == true)	
	{
		if(set_enable(true).is_error())
			msg = "FPGA enable not on";
	}

	if(msg.empty() == true)
		m_firmware_ok = true;

	if(dir_ch != nullptr)
		free(dir_ch);

	return msg;
}