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From: Jean-Jacques M. <jjm...@li...> - 2002-03-01 14:18:49
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After the via-rhine, here is something weird about the Realtek driver : I had Etherboot stop after the "(DHCP)..." and the frames were "malformed" due to the type in the mac header being 0x0000. Cause : In "rtl_transmit", the variable nstype is updated only AFTER the memcpy is done ! Moving the "nstype = htons(type)" far from the "memcpy" makes the problem disappear. The assembly output (Gcc 3.0.3) : 00000248 <rtl_transmit>: 248: 55 push %ebp 249: 57 push %edi 24a: 56 push %esi 24b: 53 push %ebx 24c: 83 ec 0c sub $0xc,%esp 24f: 8b 4c 24 24 mov 0x24(%esp,1),%ecx 253: 8b 01 mov (%ecx),%eax 255: 8b 6c 24 20 mov 0x20(%esp,1),%ebp 259: a3 20 00 00 00 mov %eax,0x20 25e: 66 8b 41 04 mov 0x4(%ecx),%ax 262: 8b 4d 18 mov 0x18(%ebp),%ecx 265: 66 a3 24 00 00 00 mov %ax,0x24 26b: 8b 01 mov (%ecx),%eax 26d: 8b 5c 24 2c mov 0x2c(%esp,1),%ebx 271: 8b 54 24 28 mov 0x28(%esp,1),%edx ;Here is "type", from the function parameters 275: a3 26 00 00 00 mov %eax,0x26 27a: 86 d6 xchg %dl,%dh ;htons(type) 27c: 66 8b 41 04 mov 0x4(%ecx),%ax 280: 66 a3 2a 00 00 00 mov %ax,0x2a 286: 0f b7 d2 movzwl %dx,%edx ;extend %edx 289: 8b 44 24 08 mov 0x8(%esp,1),%eax ; %eax=nstype (!!!Uninitialized!!!) 28d: 85 db test %ebx,%ebx 28f: 8b 74 24 30 mov 0x30(%esp,1),%esi 293: 89 54 24 08 mov %edx,0x8(%esp,1) ;nstype=htons(type) 297: 66 a3 2c 00 00 00 mov %ax,0x2c ; !!! We are using %ax, not %dx !!! ; Thus the tx_buffer.mactype is WRONG ! Let's hope it does not appear at other places in the code !!! Not that easy to trace ! Regards, -- Jean-Jacques Michel mailto:jjm...@li... Hardware Engineer - Linbox http://www.linbox.com Technopôle Metz 2000 - 152 rue de Grigy - 57070 Metz - France Tel : +33 (0)3 87 75 55 21 - Fax : +33 (0)3 87 75 19 26 |
