Re: [Qemu-devel] 0.15.0-rc2 (any version past 0.14.1) having issues with SLIRP on Windows XP host

[TeLeMan]

On Sat, Aug 6, 2011 at 04:46, Blue Swirl <address@hidden> wrote:
> On Fri, Aug 5, 2011 at 8:09 PM, Kenneth Salerno
> <address@hidden> 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.