Re: [RFC v3] tcp: Replace TCP buffer structure by an iovec array

[Laurent Vivier <lvivier@redhat.com>]

On 3/21/24 11:55, David Gibson wrote:
> On Thu, Mar 21, 2024 at 09:26:58AM +0100, Laurent Vivier wrote:
>> On 3/21/24 02:26, David Gibson wrote:
>>> On Wed, Mar 20, 2024 at 05:31:46PM +0100, Laurent Vivier wrote:
>>>> To be able to provide pointers to TCP headers and IP headers without
>>>> worrying about alignment in the structure, split the structure into
>>>> several arrays and point to each part of the frame using an iovec array.
>>>>
>>>> Using iovec also allows us to simply ignore the first entry when the
>>>> vnet length header is not needed.
>>>>
>>>> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
>>>
>>> [snip]
>>>> +static_assert(MSS4 <= sizeof(tcp4_payload[0].data));
>>>
>>> This generates a clang-tidy warning, because apparently the C11
>>> version of static_assert() requires a message - making it optional is
>>> a C2x extension.
>>>
>>> Laurent, I know you're having trouble getting the full testsuite to
>>> run (but some ideas on that later today, I hope).  But could you
>>> please add a "make cppcheck" and "make clang-tidy" to your pre-post
>>> routine.
>>>
>>
>> I'll do.
>> Thank you to have checked that.
>> Are there any other commands to run before to send?
>> Something like scripts/chekpatch.pl we have in QEMU?
>>
>> I have always the same problem with the test suite, even after a "make
>> realclean" in test (see attachment)
>> How to debug?
> 
> Huh.  Guest kernel can't find root.  That's not a fault I was
> expecting (and alas, won't be helped by the patch I have in the
> works).
> 
> What's really weird is I don't see any signs of loading the initrd
> before that failure, and with the mbuto images we're using we should
> never *leave* the initrd.  Which kind of makes sense - if it's not
> seeing the initrd, then there is indeed no root to mount.
> 
> Can you gran the full qemu command line it's trying to use?
> 
My file mbuto seems to be empty:

$ cd test/
$ make
./mbuto/mbuto -p ./passt.mem.mbuto -c lz4 -f mbuto.mem.img
Applying profile from file ./passt.mem.mbuto
depmod: WARNING: could not open modules.builtin.modinfo at 
/tmp/tmp.0Xr88SNogx/lib/modules/6.7.9-200.fc39.x86_64: No such file or directory
Size: bin  4.9M lib   15M kmod  218k total   20M compressed  4.1k
KERNEL=/boot/vmlinuz-6.7.9-200.fc39.x86_64
INITRD=/home/lvivier/Projects/passt/test/mbuto.mem.img
initramfs mounted at: /tmp/tmp.0Xr88SNogx
$ ls -l /home/lvivier/Projects/passt/test/mbuto.mem.img
-rw-r--r--. 1 lvivier lvivier 50 Mar 21 13:17 /home/lvivier/Projects/passt/test/mbuto.mem.img
$ gzip -d -  < /home/lvivier/Projects/passt/test/mbuto.mem.img|hexdump -C
00000000  30 37 30 37 30 31 30 30  30 30 30 30 30 30 30 30  |0707010000000000|
00000010  30 30 30 30 30 30 30 30  30 30 30 30 30 30 30 30  |0000000000000000|
00000020  30 30 30 30 30 30 30 30  30 30 30 30 30 31 30 30  |0000000000000100|
00000030  30 30 30 30 30 30 30 30  30 30 30 30 30 30 30 30  |0000000000000000|
*
00000060  30 30 30 30 30 42 30 30  30 30 30 30 30 30 54 52  |00000B00000000TR|
00000070  41 49 4c 45 52 21 21 21  00 00 00 00 00 00 00 00  |AILER!!!........|
00000080  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000200

Thanks,
Laurent