[PATCH v4 00/14] Introduce the lwIP network stack

[Peter Robinson]

On Wed, 19 Jun 2024 at 16:06, Jerome Forissier
<jerome.forissier at linaro.org> wrote:
>
>
>
> On 6/19/24 09:24, Ilias Apalodimas wrote:
> > Hi Tom
> >
> > On Tue, 18 Jun 2024 at 23:21, Tom Rini <trini at konsulko.com> wrote:
> >>
> >> On Mon, Jun 17, 2024 at 05:32:52PM +0200, Jerome Forissier wrote:
> >>
> >>> This is a rework of a patch series by Maxim Uvarov: "net/lwip: add lwip
> >>> library for the network stack" [1]. The goal is to introduce the lwIP TCP/IP
> >>> stack [2] [3] as an alternative to the current implementation in net/,
> >>> selectable with Kconfig, and ultimately keep only lwIP if possible. Some
> >>> reasons for doing so are:
> >>> - Make the support of HTTPS in the wget command easier. Javier T. (CC'd)
> >>> has some additional lwIP and Mbed TLS patches to do so. With that it
> >>> becomes possible to fetch and launch a distro installer such as Debian
> >>> etc. using a secure, authenticated connection directly from the U-Boot
> >>> shell. Several use cases:
> >>>   * Authentication: prevent MITM attack (third party replacing the
> >>> binary with a different one)
> >>>   * Confidentiality: prevent third parties from grabbing a copy of the
> >>> image as it is being downloaded
> >>>   * Allow connection to servers that do not support plain HTTP anymore
> >>> (this is becoming more and more common on the Internet these days)
> >>> - Possibly benefit from additional features implemented in lwIP
> >>> - Less code to maintain in U-Boot
> >>
> >> So, on a Pi 3 (rpi_3_defconfig) I see this now (and it passes normally):
> >> ========================================== FAILURES ===========================================
> >> ___________________________________ test_efi_helloworld_net ___________________________________
> >> test/py/tests/test_efi_loader.py:163: in test_efi_helloworld_net
> >>     assert expected_text in output
> >> E   AssertionError: assert 'Hello, world' in 'No UEFI binary known at 200000'
> >> ------------------------------------ Captured stdout call -------------------------------------
> >> U-Boot> tftpboot 200000 EFI/arm64/helloworld.efi
> >> Using smsc95xx_eth device
> >> TFTP from server 192.168.1.10; our IP address is 192.168.1.100
> >> Filename 'EFI/arm64/helloworld.efi'.
> >> Load address: 0x200000
> >> Loading:
> >> Bytes transferred = 4528 (11b0 hex)
> >> U-Boot> U-Boot> crc32 200000 $filesize
> >> CRC32 for 00200000 ... 002011af ==> 2b466005
> >> U-Boot> U-Boot> bootefi 200000
> >> No UEFI binary known at 200000
> >> U-Boot>
> >> =================================== short test summary info ===================================
> >> If I disable that test, it moves on to failing the same exact way for
> >> grub. If I disable the grub test too. After that, oh, a bunch of other
> >> tests get skipped because CMD_NET and similar aren't enabled now, and
> >> the tests are wrong. I'll post that as another patch by itself. After
> >> correcting for that, we're seemingly noticeably slower as I need to
> >> increase the timeout for tftp'ing my 83MiB FIT image I use for kernel
> >> testing. We no longer have the estimated speed message, so I can't as
> >> easily say how much slower it is. After increasing the timeout, the
> >> kernel boot test does work.
> >>
> >> I can note that normally it takes ~18ms to get a dhcp reply, but with
> >> lwIP it's now 132ms, and previously the kernel loaded at 2.7MiB/s
> >> (which, not great) but if that has a similar level of slowdown, could
> >> well explain it.
> >>
> >
> > Thanks for taking the time. We'll run the pytests before v5. That
> > being said, my wget tests were faster with lwIP last time I checked.
>
> The reason for the slower TFTP is the block size. lwIP supports only the
> default (512 bytes), while the legacy stack supports the 'blksize' option
> and sets CONFIG_TFTP_BLOCKSIZE=1468 by default.

This number looks like it's derived from standard ethernet frame
(1500) minus default packet sizes to get to 1468. Does LWIP have a
concept of MTU? I would have thought it would be better to use MTU if
so because it then means it's not hard coded and it can change based
on what the driver/HW supports?

Peter