[ECOS] Ethernet driver: alignment warning

[Christian Plessl <cplessl at ee dot ethz dot ch>]

Hi

Currently I'm porting a driver for NE2000 ISA network adapters to ecos 
(i386 target). I integrated the driver in the devs/eth tree of ecos. Using 
the driver directly seems to work already, but integrated in ecos the 
driver doesnt work yet.

When I compile ecos with network support I always get the following warning:

warning: alignment of `if_ne2k_netdev' is greater than maximum object file 
alignment. Using 4.


I followed the document driver_doc in the io/eth/doc directory, which 
explains how to write an ethernet driver. The warning comes from the 
initialization of the driver structures using the ETH_DRV_SC and 
NETDEVTAB_ENTRY macros.

I dont know whether I can ingore this warning safely or not!

Can anybody help?

In the remainder of this Mail I attached the output of make, a snippet of 
the source code and the same source after gcc processed the macros.


Chris


---------- gcc output ------------
make[1]: Entering directory 
`/home/cplessl/work/ram-work-net/devs/eth/ne2k/current'
i386-elf-gcc -c  -I/home/cplessl/work/ram-work-net/install/include 
-I/usr/local/pack/ecos-cvs/ecos/packages/devs/eth/ne2k/current 
-I/usr/local/pack/ecos-cvs/ecos/packages/devs/eth/ne2k/current/src 
-I/usr/local/pack/ecos-cvs/ecos/packages/devs/eth/ne2k/current/tests -I. 
-I/usr/local/pack/ecos-cvs/ecos/packages/devs/eth/ne2k/current/src/ 
-save-temps -Wall -Wpointer-arith -Wstrict-prototypes -Winline -Wundef 
-Woverloaded-virtual -g -O2 -ffunction-sections -fdata-sections -fno-rtti 
-fno-exceptions -fvtable-gc -finit-priority -Wp,-MD,src/ne2000_drv.tmp -o 
src/devs_eth_ne2k_ne2000_drv.o 
/usr/local/pack/ecos-cvs/ecos/packages/devs/eth/ne2k/current/src/ne2000_drv.c
/usr/local/pack/ecos-cvs/ecos/packages/devs/eth/ne2k/current/src/ne2000_drv.c:63: 
warning: alignment of `if_ne2k_netdev' is greater than maximum object file 
alignment. Using 4.
----------- end of gcc output --------


---------- source snippet ------------
struct if_ne2k_priv_data_t {
   snic nic_stat;
   unsigned char prom[LEN_PROM];  // content of prom
   cyg_handle_t ne2k_int_handle;   // handle to inthandler
   cyg_interrupt ne2k_interrupt;   // the inthandler itself
   bool ne2k_int_initialized;      // is the int handler initialized
   bool ne2k_int_active;           // is inthander active (attached + unmasked)
} priv_data;

ETH_DRV_SC(if_ne2k_sc,
            &priv_data,  // driver specific data
            "eth0",
            if_ne2k_start,
            if_ne2k_stop,
            if_ne2k_control,
            if_ne2k_can_send,
            if_ne2k_send,
            if_ne2k_recv,
            if_ne2k_deliver,
            if_ne2k_poll,
            if_ne2k_int_vector
);
NETDEVTAB_ENTRY(if_ne2k_netdev,
                 "if_ne2k",
                 if_ne2k_init,
                 &if_ne2k_sc);
---------- end of source snippet ------------


-----------source after macro expansion ------
struct if_ne2k_priv_data_t {
   snic nic_stat;
   unsigned char prom[16 ];
   cyg_handle_t ne2k_int_handle;
   cyg_interrupt ne2k_interrupt;
   bool ne2k_int_initialized;
   bool ne2k_int_active;
} priv_data;

static void
            if_ne2k_start (struct eth_drv_sc * if_ne2k_sc , unsigned char 
*enaddr, int flags); static void
            if_ne2k_stop (struct eth_drv_sc * if_ne2k_sc ); static int
            if_ne2k_control (struct eth_drv_sc * if_ne2k_sc , unsigned long 
key, void *data, int data_length); static int
            if_ne2k_can_send (struct eth_drv_sc * if_ne2k_sc ); static void
            if_ne2k_send (struct eth_drv_sc * if_ne2k_sc , struct 
eth_drv_sg *sg_list, int sg_len, int total, unsigned long key); static void
            if_ne2k_recv (struct eth_drv_sc * if_ne2k_sc , struct 
eth_drv_sg *sg_list, int sg_len); static void
            if_ne2k_int (struct eth_drv_sc * if_ne2k_sc ); static void
            if_ne2k_int (struct eth_drv_sc * if_ne2k_sc ); static int
            if_ne2k_int_vector
  (struct eth_drv_sc * if_ne2k_sc ); static struct 
eth_hwr_funs  if_ne2k_sc_funs = {        if_ne2k_start 
,         if_ne2k_stop ,         if_ne2k_control ,       if_ne2k_can_send 
,              if_ne2k_send ,          if_ne2k_recv ,          if_ne2k_int 
,          if_ne2k_int ,           if_ne2k_int_vector  , &eth_drv_funs, 
(struct eth_drv_funs *)0 }; struct eth_drv_sc  if_ne2k_sc  = {& 
if_ne2k_sc_funs,
            &priv_data ,
            "eth0" }; ;
static bool
                 if_ne2k_init (struct cyg_netdevtab_entry *tab); 
cyg_netdevtab_entry_t  if_ne2k_netdev  __attribute__((section ( 
".ecos.table." "netdev"   ".data" )))   = {
                 "if_ne2k" ,             if_ne2k_init ,
                 &if_ne2k_sc  }; ;

-----------end of source after macro expansion ------

--
Christian Plessl <cplessl@ee.ethz.ch>