kern/143285: [em] [regression] jumbo frames broken in 8.0

[S Smirnov]

>Number:         143285
>Category:       kern
>Synopsis:       [em] [regression] jumbo frames broken in 8.0
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Jan 27 10:30:01 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator:     S Smirnov
>Release:        8.0-RELEASE p1
>Organization:
>Environment:
FreeBSD server.net 8.0-RELEASE-p1 FreeBSD 8.0-RELEASE-p1 #2 r200053M: Mon Dec 14 13:41:23 MSK 2009     root at server.net:/usr/obj/usr/src/sys/AMD64  amd64
>Description:
8.0 side:
em1 at pci0:4:0:1: class=0x020000 card=0x000015d9 chip=0x10968086 rev=0x01 hdr=0x00
    vendor     = 'Intel Corporation'
    device     = 'Intel PRO/1000 EB (Intel PRO/1000 EB)'
    class      = network
    subclass   = ethernet
    bar   [10] = type Memory, range 32, base 0xc8220000, size 131072, enabled
    bar   [18] = type I/O Port, range 32, base 0x2020, size 32, enabled
    cap 01[c8] = powerspec 2  supports D0 D3  current D0
    cap 05[d0] = MSI supports 1 message, 64 bit enabled with 1 message
    cap 10[e0] = PCI-Express 1 endpoint max data 128(256) link x4(x4)

7.2 side:
em1 at pci0:15:0:0:        class=0x020000 card=0x109a15d9 chip=0x109a8086 rev=0x00 hdr=0x00
    vendor     = 'Intel Corporation'
    device     = '82573L Intel PRO/1000 PL Network Adaptor'
    class      = network
    subclass   = ethernet
    bar   [10] = type Memory, range 32, base 0xd0300000, size 131072, enabled
    bar   [18] = type I/O Port, range 32, base 0x3000, size 32, enabled
    cap 01[c8] = powerspec 2  supports D0 D3  current D0
    cap 05[d0] = MSI supports 1 message, 64 bit enabled with 1 message
    cap 10[e0] = PCI-Express 1 endpoint

interconnected with copper cable directly
ifconfig em1 10.0.0.1/30 mtu 9000
when rxcsum and txcsum are not disabled, I can ping only other side
no data in tcpdump
>How-To-Repeat:

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: