[OpenWrt-Devel] [PATCH] ramips: mt7621: use lzma-loader for D-Link DIR-860L B1

[Szabolcs Hubai]

Hello,

Stijn Segers <foss at volatilesystems.org> ezt írta (időpont: 2020. ápr.
20., H, 9:25):
>
> Hi Szabolcs,
>
> Op zondag 19 april 2020 om 20u49 schreef Szabolcs Hubai
> <szab.hu at gmail.com>:
> > This device has trouble extracting big kernel from flash,
> > and supports LZMA compressed kernels only.
> >
> > Using OpenWrt kernel loader saves us 64 KB compared to the dictionary
> > size limiting workaround.
> >
> > Factory image sizes (commit: 5f126c541a74) with "CONFIG_ALL_KMODS=y":
> > - original ("-d23", default): 4784188 bytes, LZMA ERROR 1
> > - with "-d19": 4915260, LZMA ERROR 1
> > - with "-d18": 4915260, diff to original: +128 KB
> > - with "-d17": 4980796, diff to original: +192 KB
> > - with this patch: 4849724, diff to original: +64 KB
> >
> > To save some CPU cycle, use minimal compression ("-a0") for the LZMA
> > compressed uImage.
> >
> > The most robust solution would use a different loader,
> > which reads the compressed kernel directly from the flash.
> > See the thread at [0] for more details!
>
> Thanks for giving the DIR-860L some love. I'd like to test (in fact I
> already
> did with your previous patches) and hook up serial, because first boot
> will
> work but any reboot (whether I change settings or not) will just give
> me a
> blinking orange LED. Like clockwork.
>
> Would you happen to have any pointers (or pictures) on how to open the
> case?
> I have unscrewed the bottom but there seem to be latches on the inside
> (judging
> from the FCC pictures) and I am unable to pry it open.
>
> Thanks and sorry for the topic hijack :-).
>
> Stijn
>

I got my clue from the "D-LINK DIR-860L - disassemble" titled YouTube video. [0]
In short:
- 3 screws on the bottom, under the pads: if you are looking at the
bottom of the router, the screws are under the left, the right and the
bottom pads
- one, "DIR-860L" titled sticker on the top, with a "cut in" starting
point in the front, where the leds reside
- 3 screws on the top, under the sticker

Disassemble:
- get off the pads (they won't stick back after a few days ;), use
very thin double sided sticker to help them)
- get the bottom screws
- peel off the rounded sticker from the top with thin but flexible
knife or razor blade, etc ...
- get the upper screws
- slide the front and rear half vertically a little
- separate them

The serial settings can be found on the wiki [1]:
- Pinout: TX, GND, 3v3, empty, RX
- Bits per second: 57600
- Data bits: 8
- Parity: None
- Stop bits: 1
- Flow control: None

I have a CP2102 USB to TTL module, and used with "minicom -D /dev/ttyUSB0".


Intereestingly, when I connected with serial to the router it was
sometime unstable:
* refuse to start
* freeze at boot soon after: "Error applying setting, reverse things
back" messge

Other than this, I have no problem with k5.4.



[0]: https://youtu.be/tf7nMqdUKD4
[1]: https://openwrt.org/toh/d-link/dir-860l#access_with_serial_cable


--
Regards,
Szabolcs


>
> >
> > [0]
> > http://lists.infradead.org/pipermail/openwrt-devel/2020-April/022926.html
> >
> > Signed-off-by: Szabolcs Hubai <szab.hu at gmail.com>
> > ---
> >  target/linux/ramips/image/mt7621.mk | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/target/linux/ramips/image/mt7621.mk
> > b/target/linux/ramips/image/mt7621.mk
> > index aa6836d50a..e954f730da 100644
> > --- a/target/linux/ramips/image/mt7621.mk
> > +++ b/target/linux/ramips/image/mt7621.mk
> > @@ -218,7 +218,9 @@ define Device/dlink_dir-860l-b1
> >    $(Device/seama)
> >    BLOCKSIZE := 64k
> >    SEAMA_SIGNATURE := wrgac13_dlink.2013gui_dir860lb
> > -  KERNEL := kernel-bin | append-dtb | relocate-kernel | lzma |
> > uImage lzma
> > +  LOADER_TYPE := bin
> > +  KERNEL := kernel-bin | append-dtb | lzma | loader-kernel | \
> > +  relocate-kernel | lzma -a0 | uImage lzma
> >    IMAGE_SIZE := 16064k
> >    DEVICE_VENDOR := D-Link
> >    DEVICE_MODEL := DIR-860L
> > --
> > 2.17.1
> >
> >
> > _______________________________________________
> > openwrt-devel mailing list
> > openwrt-devel at lists.openwrt.org
> > https://lists.openwrt.org/mailman/listinfo/openwrt-devel
>
>

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