On Sat, Aug 6, 2011 at 1:33 PM, Anthony Liguori <anth...@codemonkey.ws> wrote:
> On 08/05/2011 10:25 PM, TeLeMan wrote:
>>
>> On Sat, Aug 6, 2011 at 04:46, Blue Swirl<blauwir...@gmail.com> wrote:
>>>
>>> On Fri, Aug 5, 2011 at 8:09 PM, Kenneth Salerno
>>> <kennethsale...@yahoo.com> wrote:
>>>>
>>>> Hi,
>>>>
>>>> I'm not sure if any defaults (build or runtime) have changed since
>>>> 0.14.1, but I can no longer get the following to work anymore for QEMU
>>>> versions 0.15.0-rc2 or recent development builds:
>>>>
>>>> -device e1000,netdev=mynet0 -netdev type=user,id=mynet0 ...
>>>>
>>>> Works great in 0.14.1 however.
>>>>
>>>> From the QEMU console, "info networking" shows the NIC e1000 and the
>>>> VLAN correctly setup, the guest (RHEL 6.1 x86_64) has its NIC recognized
>>>> and
>>>> networking setup, just can't seem to communicate with the gateway
>>>> (10.0.2.2). The only difference I see in the console is cosmetic
>>>> (restricted=off rather than restricted=n).
>>>>
>>>> Host OS: Windows XP
>>>> Build env: i686-pc-mingw32-gcc 4.5.2, binutils 2.21.53.20110731 i386pe
>>>> Runtime env: Cygwin 1.7.9 2011-03-29, SDL 1.2.14, mingw32-glib 2.28.1-1,
>>>> mingw32-gettext 0.18.1-2
>>>> Guest OS: RHEL 6.1
>>>>
>>>> Is it just me?
>>>
>>> No, this is fallout from glib use:
>>> http://lists.nongnu.org/archive/html/qemu-devel/2011-08/msg00134.html
>>>
>>> The fix is to rewrite structures without using GCC bit fields.
>>
>> -mms-bitfields affects all byte-alignments in a structure. For example,
>> struct s
>> {
>> uint8_t a;
>> uint32_t b;
>> } __attribute__((packed));
>>
>> sizeof(s) is 5 without -mms-bitfields but sizeof(s) is 8 with
>> -mms-bitfields.
>
> If you can identify the offending structs, you can do:
>
> #pragma pack(push,1)
>
> struct s
> {
> uint8_t a;
> uint32_t b;
> } __attribute__((packed));
>
> #pragma pack(pop)
I grepped the tree for ((packed)). The only two places where bit
fields are used with packed structs are in SLIRP:
struct ip {
#ifdef HOST_WORDS_BIGENDIAN
u_int ip_v:4, /* version */
ip_hl:4; /* header length */
#else
u_int ip_hl:4, /* header length */
ip_v:4; /* version */
#endif
uint8_t ip_tos; /* type of service */
uint16_t ip_len; /* total length */
uint16_t ip_id; /* identification */
uint16_t ip_off; /* fragment offset field */
#define IP_DF 0x4000 /* don't fragment flag */
#define IP_MF 0x2000 /* more fragments flag */
#define IP_OFFMASK 0x1fff /* mask for fragmenting bits */
uint8_t ip_ttl; /* time to live */
uint8_t ip_p; /* protocol */
uint16_t ip_sum; /* checksum */
struct in_addr ip_src,ip_dst; /* source and dest address */
} __attribute__((packed));
struct ip_timestamp {
uint8_t ipt_code; /* IPOPT_TS */
uint8_t ipt_len; /* size of structure (variable) */
uint8_t ipt_ptr; /* index of current entry */
#ifdef HOST_WORDS_BIGENDIAN
u_int ipt_oflw:4, /* overflow counter */
ipt_flg:4; /* flags, see below */
#else
u_int ipt_flg:4, /* flags, see below */
ipt_oflw:4; /* overflow counter */
#endif
union ipt_timestamp {
n_long ipt_time[1];
struct ipt_ta {
struct in_addr ipt_addr;
n_long ipt_time;
} ipt_ta[1];
} ipt_timestamp;
} __attribute__((packed));
I'd avoid the bit fields altogether in both cases, then also the
#ifdeffery could be removed.
