[U-Boot] [PATCH] TCP and wget implementation v4

[Joe Hershberger]

On Wed, Jan 3, 2018 at 5:01 PM, Duncan Hare <dh at synoia.com> wrote:
>> >>>selects the LIB_RAND feature since it is required.
>> >
>> > Thanks: will be in u-boot/cmd/Kconfig
>> >
>> >>Are we lookin at a series of patches, or a concurrent set?
>> >
>> > At this time a series of three, but I'd take advice on the preferred
>> > procedure.
>>
>> Remember that the goal is to be atomic.
>>
>> You should be able to build and use U-Boot after each patch.
>>
>> Also, any changes to existing code that is not changing behavior but
>> simply making way for new functionality should be done separately.
>> Thanks
>> -Joe
>
> A note on this TCP implementation. In TCP the transmitting TCP
> guarantees delivery of a stream, and the receiving TCP guarantees
> ordered of delivery of the stream. In this implementation The
> kernel memory buffer and the TCP sequence number is used to order the stream.
> for the application, and the application is the kernel itself. wget is
> not considered the application, and does receive packets "out of order."

It seems like it would be possible to just store off a packet that is
ahead of its neighbor and not call any upper handler until the needed
packet arrives. Then all upper layers wouldn't need to know about the
reordering.

>
> This places a constraint on the incoming data stream. All
> (disordered) packets received before the HTTP header are
> ignored, which means the sending TCP will re-transmit them. This forced
> re-transmission could be avoided with a change to reprocess the
> incoming packet stream back to the first packet received, directly
> following processing the TCP header.
>
> This behavior was detected and failed downloads fixed in tests
> downloading Linux kernels from the cloud.
>
> Advice on the reset buffer approach are invited. It requires an
> interface between the wget application to reset the buffer index.

Between wget and what? The TCP implementation? It seems like something
that should be abstracted from wget.

>
> Joe Thanks, Good advice, based on that the order of 3 patches is:
>
> (1) Prepares the interfaces, no new behavior, CONFIG-TCP is introduced.
> net/Kconfig
> net/net.c
> net/ping.c
> include/net.h
>
> (2) Introduces TCP
> net/tcp.c
> net/tcp.h
> net/Makefile
>
> (3) Introduces wget, CONFIG-WGET introduced
> cmd/Kconfig
> cmd/net.c
> net/wget.c
> net/wget.h
>
>
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