Hi everyone,

I’m using u-boot-2015.07 in one of my project based on vpac270 soc module.

u-boot is well configured and build is fine without error.

Gcc is v3.4.5 and glibc v2.3.6 built by crosstool 0.43 for arm-softfloat-linux-gnu

My problem is when i use DHCP command to retrieve a file from my TFTP server, i can’t get any IP from the DHCP server.

After analysing ethernet frames on server side i found that frame do not arrive at all on server.

After checking debug détails on U-boot, it seem bootp frame is not good because of some 0x00 paddings Inside the frame. (at end of header for example)

If i add the attribute packed to the bootp header struct and ethernet header, now all is working fine !

In net/bootp.h :

struct bootp_hdr {

u8 bp_op; /* Operation */

# define OP_BOOTREQUEST 1

# define OP_BOOTREPLY 2

u8 bp_htype; /* Hardware type */

# define HWT_ETHER 1

u8 bp_hlen; /* Hardware address length */

# define HWL_ETHER 6

u8 bp_hops; /* Hop count (gateway thing) */

u32 bp_id; /* Transaction ID */

u16 bp_secs; /* Seconds since boot */

u16 bp_spare1; /* Alignment */

struct in_addr bp_ciaddr; /* Client IP address */

struct in_addr bp_yiaddr; /* Your (client) IP address */

struct in_addr bp_siaddr; /* Server IP address */

struct in_addr bp_giaddr; /* Gateway IP address */

u8 bp_chaddr[16]; /* Client hardware address */

char bp_sname[64]; /* Server host name */

char bp_file[128]; /* Boot file name */

char bp_vend[OPT_FIELD_SIZE]; /* Vendor information */

} __attribute__((packed));

#define BOOTP_HDR_SIZE sizeof(struct bootp_hdr)

And in include/net.h

struct ethernet_hdr {

u8 et_dest[6]; /* Destination node */

u8 et_src[6]; /* Source node */

u16 et_protlen; /* Protocol or length */

} __attribute__((packed));

I think the uboot src should work as is, because I have checked uboot source modification since 2015.07, but no changes on the struct definition and header_size still made with sizeof(struct).

So i think, the problem come from my side and perhaps from gcc itself.

But i don’t understand why gcc should pack these structs.. i think normal use is to not pack.. except if makefile include some build option to do that, my gcc toolchain do not understand..

Someone can help me to understand what i made wrong ? and help me to resolve this problem without patching ?