From: Skip Tavakkolian <skip.tavakkolian@gmail.com>
To: 9fans <9fans@9fans.net>
Subject: Re: [9fans] Plan9 on Raspberry Pi 400?
Date: Sat, 16 Jan 2021 23:11:02 -0800 [thread overview]
Message-ID: <CAJSxfmK=_rgZZRNTz7Og3cpMjtcTSNB1=vg2efUEGv308_ZD=g@mail.gmail.com> (raw)
In-Reply-To: <27B589BD-55D2-4A68-BCD3-AEACF0151CC3@iitbombay.org>
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I went down the eeprom rabbithole a bit. To access and manipulate RPI4's
eeprom directly,
Plan 9 would need to support a device like /dev/vchiq (VideoCore interface)
on Linux:
https://github.com/raspberrypi/linux/blob/rpi-3.2.27/drivers/misc/vc04_services/interface/vchiq_arm/vchiq_arm.c#L334
The rest of the tools (e.g. rpi-eeprom-update) eventually use vcgencmd
which ioctl into /dev/vchiq.
My /dev/mmcblk comment was wrong.
On Sat, Jan 16, 2021 at 2:15 PM Bakul Shah <bakul@iitbombay.org> wrote:
> I believe all it takes is the presence of recover.bin file on the dos
> partition.
> You still need an updated eeprom image for it to flash the real eeprom with
> but preparing this image doesn't require any h/w access. Unless things
> have changed in the last year.
>
> On Jan 16, 2021, at 1:24 PM, Skip Tavakkolian <skip.tavakkolian@gmail.com>
> wrote:
>
> regarding /dev/serial, this should be helpful for anyone wanting to set up
> netboot.
>
> If you have a number of RPI's that netboot, the way that the common
> config.txt is segmented for each board is by using the '[serial number in
> hex]' section headers. Unfortunately, netboot also requires changing the
> BOOT_ORDER parameter in EEPROM, which requires access to /dev/mmcblk* and
> some way of generating the proper .bin format. So Linux is still needed for
> the initial setup.
>
> On Sat, Jan 16, 2021 at 9:13 AM Richard Miller <9fans@hamnavoe.com> wrote:
>
>> > I didn't realise the 9pi image was not up to date.
>> > I'll put a new one on 9p.io today.
>>
>> I've done that. Sorry for letting it get out of sync with the kernel
>> source.
>>
>> The new contrib/miller/9pi.img.gz has
>> - the latest firmware files from the raspberry pi github
>> - the update to initialise xhci firmware for pi400 and recent pi4 boards
>> - a tweak to the pi4 gigabit ethernet driver to allow jumbo packets
>> - a new /dev/serial device from which you can read the board serial
>> number (I forget why)
>>
>> Nothing outside the kernel has changed from the previous image.
>>
>
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next prev parent reply other threads:[~2021-01-17 7:11 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-16 17:12 Richard Miller
2021-01-16 21:24 ` Skip Tavakkolian
2021-01-16 22:14 ` Bakul Shah
2021-01-17 7:11 ` Skip Tavakkolian [this message]
-- strict thread matches above, loose matches on Subject: below --
2021-01-14 21:34 Mack Wallace
2021-01-14 23:05 ` Stuart Morrow
2021-01-14 23:37 ` Mack Wallace
2021-01-15 1:15 ` Skip Tavakkolian
2021-01-15 18:44 ` Mack Wallace
2021-01-15 19:54 ` Mack Wallace
2021-01-15 21:17 ` Michael Engel
2021-01-15 21:58 ` Stuart Morrow
2021-01-15 22:32 ` Bakul Shah
2021-01-15 22:52 ` Michael Engel
2021-01-16 0:31 ` Mack Wallace
2021-01-16 1:01 ` Michael Engel
2021-01-16 10:24 ` Richard Miller
2021-01-16 11:28 ` Michael Engel
2021-01-18 14:51 ` Richard Miller
2021-01-18 15:42 ` Mack Wallace
2021-01-18 16:54 ` ori
2021-01-19 8:20 ` hiro
2021-01-19 0:54 ` Stuart Morrow
2021-01-19 4:13 ` Lucio De Re
2021-01-19 9:52 ` Richard Miller
2021-01-20 15:25 ` Mack Wallace
2021-01-16 3:03 ` Bakul Shah
2021-01-16 7:19 ` Skip Tavakkolian
2021-01-16 16:15 ` Skip Tavakkolian
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