Re: [Qemu-devel] [PULL] slirp: Fix issues with -mms-bitfields

[Jan Kiszka]

On 2011-08-25 03:14, TeLeMan wrote:
> On Wed, Aug 24, 2011 at 17:11, Jan Kiszka <address@hidden> wrote:
>> On 2011-08-23 12:49, TeLeMan wrote:
>>> On Sun, Aug 21, 2011 at 04:00, Stefan Weil <address@hidden> wrote:
>>>> Am 15.08.2011 08:39, schrieb Jan Kiszka:
>>>>>
>>>>> The following changes since commit
>>>>> 3b6ffe50300f13240e1b46420ad05da1116df410:
>>>>>
>>>>> hw/scsi-bus.c: Fix use of uninitialised variable (2011-08-14 19:34:25
>>>>> +0000)
>>>>>
>>>>> are available in the git repository at:
>>>>> git://git.kiszka.org/qemu.git queues/slirp
>>>>>
>>>>> Jan Kiszka (1):
>>>>> slirp: Fix bit field types in IP header structs
>>>>>
>>>>> slirp/ip.h | 8 ++++----
>>>>> slirp/tcp.h | 4 ++--
>>>>> 2 files changed, 6 insertions(+), 6 deletions(-)
>>>>>
>>>>> ---
>>>>>
>>>>> slirp: Fix bit field types in IP header structs
>>>>>
>>>>> -mms-bitfields prevents that the bitfields in current IP header structs
>>>>> are packed into a single byte as it is required. Fix this by using
>>>>> uint8_t as backing type.
>>>>>
>>>>> Signed-off-by: Jan Kiszka <address@hidden>
>>>>> ---
>>>>> slirp/ip.h | 8 ++++----
>>>>> slirp/tcp.h | 4 ++--
>>>>> 2 files changed, 6 insertions(+), 6 deletions(-)
>>>>>
>>>>> diff --git a/slirp/ip.h b/slirp/ip.h
>>>>> index 48ea38e..72dbe9a 100644
>>>>> --- a/slirp/ip.h
>>>>> +++ b/slirp/ip.h
>>>>> @@ -74,10 +74,10 @@ typedef uint32_t n_long; /* long as received from the
>>>>> net */
>>>>> */
>>>>> struct ip {
>>>>> #ifdef HOST_WORDS_BIGENDIAN
>>>>> - u_int ip_v:4, /* version */
>>>>> + uint8_t ip_v:4, /* version */
>>>>> ip_hl:4; /* header length */
>>>>> #else
>>>>> - u_int ip_hl:4, /* header length */
>>>>> + uint8_t ip_hl:4, /* header length */
>>>>> ip_v:4; /* version */
>>>>> #endif
>>>>> uint8_t ip_tos; /* type of service */
>>>>> @@ -140,10 +140,10 @@ struct ip_timestamp {
>>>>> 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 */
>>>>> + uint8_t ipt_oflw:4, /* overflow counter */
>>>>> ipt_flg:4; /* flags, see below */
>>>>> #else
>>>>> - u_int ipt_flg:4, /* flags, see below */
>>>>> + uint8_t ipt_flg:4, /* flags, see below */
>>>>> ipt_oflw:4; /* overflow counter */
>>>>> #endif
>>>>> union ipt_timestamp {
>>>>> diff --git a/slirp/tcp.h b/slirp/tcp.h
>>>>> index 9d06836..b3817cb 100644
>>>>> --- a/slirp/tcp.h
>>>>> +++ b/slirp/tcp.h
>>>>> @@ -51,10 +51,10 @@ struct tcphdr {
>>>>> tcp_seq th_seq; /* sequence number */
>>>>> tcp_seq th_ack; /* acknowledgement number */
>>>>> #ifdef HOST_WORDS_BIGENDIAN
>>>>> - u_int th_off:4, /* data offset */
>>>>> + uint8_t th_off:4, /* data offset */
>>>>> th_x2:4; /* (unused) */
>>>>> #else
>>>>> - u_int th_x2:4, /* (unused) */
>>>>> + uint8_t th_x2:4, /* (unused) */
>>>>> th_off:4; /* data offset */
>>>>> #endif
>>>>> uint8_t th_flags;
>>>>
>>>> Tested-by: Stefan Weil <address@hidden>
>>>>
>>> slirp is still broken on my mingw32. I used "#progma
>>> pack(push,1)/#progma pack(pop)" to resolve this issue.
>>
>> Can you drill down to the bottom of this problem? What fields in what
>> struct are not properly packed? Maybe this is now a compiler bug, so
>> comparing versions may make sense as well.
> arphdr.ar_sip is not aligned on  a 4-byte boundary. See my previous post:
> http://lists.gnu.org/archive/html/qemu-devel/2011-08/msg00964.html

What a mess. Do we really have to go through all 257 packed data structs
in QEMU and add these MS compat bits to all potentially affected ones?

Jan

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