RPi3b+ boards are detected as RPi3b when using os_prefix option #1720

alfonsosanchezbeato · 2022-04-11T16:53:17Z

Describe the bug
When using the os_prefix option, RPi3b+ boards are detected as RPi3b.

To reproduce
Copy dtbs, kernel, initrd, and cmdline.txt to a folder in the boot partition, and set os_config=<dir> in config.txt.

Expected behaviour
An RPI3b+ should be detected:

$ cat /proc/device-tree/compatible
raspberrypi,3-model-b-plus\0brcm,bcm2837\0

(this is the behaviour when os_prefix is not used)
Actual behaviour
An RPI3b is detected:

$ cat /proc/device-tree/compatible
raspberrypi,3-model-b\0brcm,bcm2837\0

One of the side effects that is produced is that the ethernet MAC is set to a randon number on each boot.

System

Which model of Raspberry Pi? e.g. Pi3B+, PiZeroW
Pi3B+
Which OS and version (cat /etc/rpi-issue)?
Ubuntu 22.04
Which firmware version (vcgencmd version)?
1.20211118
Which kernel version (uname -a)?
5.15.0

Logs
NA

Additional context
NA

The text was updated successfully, but these errors were encountered:

pelwell · 2022-04-11T17:18:22Z

Please post the content of config.txt? You can omit blank lines and comments.

alfonsosanchezbeato · 2022-04-12T09:16:04Z

This would be the config.txt:

[all]
kernel=kernel.img
cmdline=cmdline.txt
initramfs initrd.img followkernel
os_prefix=/systems/20220411/kernel/

[pi4]
max_framebuffers=2
arm_boost=1

[all]
dtparam=audio=on
dtparam=i2c_arm=on
dtparam=spi=on

[cm4]
dtoverlay=dwc2,dr_mode=host

[all]
dtoverlay=vc4-fkms-v3d,cma-128

arm_64bit=1
dtoverlay=dwc2
enable_uart=1

juergh · 2022-04-12T09:55:32Z

Not sure if this is related but overlay_map.dtb and vc4-fkms-v3d are not loaded if os_prefix is set. But dwc2 is.

And the DTB for 3b is loaded instead of 3b+?? I guess that would explain the MAC issue...

Without os_prefix:

MESS:00:00:04.772705:0: brfs: File read: /mfs/sd/initrd.img
MESS:00:00:04.776583:0: Loading 'initrd.img' to 0x0 size 0x119bee7
MESS:00:00:04.803253:0: initramfs loaded to 0x2de64000 (size 0x119bee7)
MESS:00:00:04.812604:0: dtb_file 'bcm2710-rpi-3-b-plus.dtb'
MESS:00:00:04.816487:0: brfs: File read: 18464487 bytes
MESS:00:00:04.829552:0: brfs: File read: /mfs/sd/bcm2710-rpi-3-b-plus.dtb
MESS:00:00:04.834642:0: Loading 'bcm2710-rpi-3-b-plus.dtb' to 0x100 size 0x7c42
MESS:00:00:04.856150:0: brfs: File read: 31810 bytes
MESS:00:00:04.871718:0: brfs: File read: /mfs/sd/overlays/overlay_map.dtb
MESS:00:00:04.959349:0: brfs: File read: 1783 bytes
MESS:00:00:04.965703:0: brfs: File read: /mfs/sd/config.txt
MESS:00:00:04.969694:0: dtparam: audio=on
MESS:00:00:04.984547:0: dtparam: i2c_arm=on
MESS:00:00:04.996004:0: dtparam: spi=on
MESS:00:00:05.006739:0: brfs: File read: 414 bytes
MESS:00:00:05.016282:0: brfs: File read: /mfs/sd/overlays/vc4-fkms-v3d.dtbo
MESS:00:00:05.042239:0: Loaded overlay 'vc4-fkms-v3d'
MESS:00:00:05.045591:0: dtparam: cma-128=true
MESS:00:00:05.087963:0: brfs: File read: 1446 bytes
MESS:00:00:05.096529:0: brfs: File read: /mfs/sd/overlays/dwc2.dtbo
MESS:00:00:05.108476:0: Loaded overlay 'dwc2'

With os_prefix:

MESS:00:00:04.802471:0: brfs: File read: /mfs/sd/piboot/ubuntu/pi-kernel_447.snap/initrd.img
MESS:00:00:04.809219:0: Loading '/piboot/ubuntu/pi-kernel_447.snap/initrd.img' to 0x0 size 0x119bee7
MESS:00:00:04.838832:0: initramfs loaded to 0x2de64000 (size 0x119bee7)
MESS:00:00:04.848180:0: dtb_file 'bcm2710-rpi-3-b-plus.dtb'
MESS:00:00:04.852073:0: brfs: File read: 18464487 bytes
MESS:00:00:04.861950:0: dtb_file 'bcm2710-rpi-3-b.dtb'
MESS:00:00:04.871646:0: brfs: File read: /mfs/sd/piboot/ubuntu/pi-kernel_447.snap/bcm2710-rpi-3-b.dtb
MESS:00:00:04.879180:0: Loading '/piboot/ubuntu/pi-kernel_447.snap/bcm2710-rpi-3-b.dtb' to 0x100 size 0x79df
MESS:00:00:04.902948:0: brfs: File read: 31199 bytes
MESS:00:00:05.006741:0: brfs: File read: /mfs/sd/config.txt
MESS:00:00:05.010738:0: dtparam: audio=on
MESS:00:00:05.025268:0: dtparam: i2c_arm=on
MESS:00:00:05.036669:0: dtparam: spi=on
MESS:00:00:05.046726:0: brfs: File read: 413 bytes
MESS:00:00:05.065435:0: Failed to load overlay 'vc4-fkms-v3d'
MESS:00:00:05.074673:0: brfs: File read: /mfs/sd/piboot/ubuntu/pi-kernel_447.snap/overlays/dwc2.dtbo
MESS:00:00:05.089478:0: Loaded overlay 'dwc2'

pelwell · 2022-04-12T10:48:49Z

With os_prefix=foo/ (and os_prefix=/foo/) it's working for me:

Raspberry Pi Bootcode
Read File: config.txt, 2121
Read File: start.elf, 2966048 (bytes)
Read File: fixup.dat, 7221 (bytes)
MESS:00:00:01.450876:0: brfs: File read: /mfs/sd/config.txt
MESS:00:00:01.456133:0: brfs: File read: 2121 bytes
MESS:00:00:01.551765:0: brfs: File read: /mfs/sd/config.txt
MESS:00:00:02.407803:0: gpioman: gpioman_get_pin_num: pin DISPLAY_DSI_PORT not defined
MESS:00:00:02.416190:0: *** Restart logging
MESS:00:00:02.418681:0: brfs: File read: 2121 bytes
MESS:00:00:02.459392:0: HDMI0: hdmi_pixel_encoding: 162000000
MESS:00:00:02.483199:0: dtb_file 'bcm2710-rpi-3-b-plus.dtb'
MESS:00:00:02.494207:0: brfs: File read: /mfs/sd/foo/bcm2710-rpi-3-b-plus.dtb
MESS:00:00:02.499653:0: Loading '/foo/bcm2710-rpi-3-b-plus.dtb' to 0x100 size 0x7c2e
MESS:00:00:02.521824:0: brfs: File read: 31790 bytes
MESS:00:00:02.536119:0: brfs: File read: /mfs/sd/foo/overlays/overlay_map.dtb
MESS:00:00:02.624321:0: brfs: File read: 1783 bytes
MESS:00:00:02.632774:0: brfs: File read: /mfs/sd/config.txt
MESS:00:00:02.637266:0: dtparam: audio=on
MESS:00:00:02.652310:0: brfs: File read: 2121 bytes
MESS:00:00:02.670759:0: brfs: File read: /mfs/sd/foo/overlays/vc4-kms-v3d.dtbo
MESS:00:00:02.725628:0: Loaded overlay 'vc4-kms-v3d'
MESS:00:00:02.839741:0: brfs: File read: 2703 bytes
MESS:00:00:02.847211:0: brfs: File read: /mfs/sd/foo/cmdline.txt
MESS:00:00:02.851558:0: Read command line from file '/foo/cmdline.txt':
MESS:00:00:02.857857:0: 'console=serial0,115200 console=tty1 root=PARTUUID=ae7b131e-02 rootfstype=ext4 fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles'
MESS:00:00:02.891406:0: gpioman: gpioman_get_pin_num: pin EMMC_ENABLE not defined
MESS:00:00:03.349380:0: brfs: File read: 148 bytes
MESS:00:00:03.790304:0: brfs: File read: /mfs/sd/foo/kernel7.img
MESS:00:00:03.794596:0: Loading '/foo/kernel7.img' to 0x8000 size 0x64ae60
MESS:00:00:03.801199:0: Device tree loaded to 0x2eff7d00 (size 0x82c6)
MESS:00:00:03.808647:0: uart: Set PL011 baud rate to 103448.300000 Hz
MESS:00:00:03.815130:0: uart: Baud rate change done...
MESS:00:00:03.818544:0: uart: Baud rate
Raspbian GNU/Linux 11 raspberrypi ttyS0

raspberrypi login: pi
Password:
Linux raspberrypi 5.15.32-v7+ #1538 SMP Thu Mar 31 19:38:48 BST 2022 armv7l

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Tue Apr 12 11:43:09 BST 2022 on tty1
pi@raspberrypi:~$ tail /proc/cpuinfo
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xd03
CPU revision    : 4

Hardware        : BCM2835
Revision        : 2a020d3
Serial          : 00000000eb4751ef
Model           : Raspberry Pi 3 Model B Plus Rev 1.3
pi@raspberrypi:~$

What do you have in your os_prefix folder? I created mine with:

$ cd /boot/
$ sudo mkdir -p foo/overlays
$ sudo cp *.img *.dtb cmdline.txt foo
$ sudo cp overlays/* foo/overlays/

juergh · 2022-04-12T12:09:02Z

foo works but piboot/ubuntu/pi-kernel_999.snap doesn't. Is there a size limit on os_prefix? Or a hierarchical limitation? If I change foo to a 40-char name it falls over.

pelwell · 2022-04-12T12:50:20Z

It's looking as though there is an overall path limit of 63 bytes including the /mfs/sd/ prefix) somewhere, which is shorter than I expected. The longest dtb filename is 24 characters, which currently would give a maximum os_prefix length of 30 characters. However, the longest overlay name is 37 characters, plus 9 characters for overlays/, which brings the maximum safe os_prefix directory name length down to a mere 8(!) characters.

This restriction is completely unexpected - I thought the limit for prefix + file path (without /mfs/sd/) would be over 80 characters, leading to a maximum os_prefix of 40 characters, but the bottleneck appears to be lower down the file handling stack.

juergh · 2022-04-13T06:47:55Z

So this is treated as a pi firmware bug then?

…

On Tue, Apr 12, 2022 at 2:50 PM Phil Elwell ***@***.***> wrote: It's looking as though there is an overall path limit of 63 bytes including the /mfs/sd/ prefix) somewhere, which is shorter than I expected. The longest dtb filename is 24 characters, which currently would give a maximum os_prefix length of 30 characters. However, the longest overlay name is 37 characters, plus 9 characters for overlays/, which brings the maximum safe os_prefix directory name length down to a mere 8 characters. This restriction is completely unexpected - I thought the limit for prefix + file path (without /mfs/sd/) would be over 80 characters, leading to a maximum os_prefix of 40 characters, but the bottleneck appears to be lower down the file handling stack. — Reply to this email directly, view it on GitHub <#1720 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAI7NWQ2ESLGZLXF24GTY3TVEVWRPANCNFSM5TDZ5URQ> . You are receiving this because you commented.Message ID: ***@***.***>

pelwell · 2022-04-13T09:19:32Z

It's somewhere between a bug and a limitation. I hope the limit can be increased, but there will always be a limit.

What would you consider an acceptable maximum path length?

pelwell · 2022-04-13T09:41:02Z

Would you be happy with a maximum os_prefix length (excluding the trailing /) of 64?:

001418.401: brfs: File read: /mfs/sd/config.txt
001423.817: brfs: File read: 2243 bytes
001528.106: brfs: File read: /mfs/sd/config.txt
002392.671: gpioman: gpioman_get_pin_num: pin DISPLAY_DSI_PORT not defined
002400.298: gpioman: gpioman_get_pin_num: pin EMMC_ENABLE not defined
002407.389: *** Restart logging
002410.017: brfs: File read: 2243 bytes
002450.889: HDMI0: hdmi_pixel_encoding: 162000000
002480.057: dtb_file 'bcm2710-rpi-3-b-plus.dtb'
002491.181: dtb_file 'bcm2710-rpi-3-b.dtb'
002502.935: brfs: File read: /mfs/sd/0123456789012345678901234567890123456789012345678901234567890123/bcm2710-rpi-3-b.dtb
002513.247: Loading '0123456789012345678901234567890123456789012345678901234567890123/bcm2710-rpi-3-b.dtb' to 0x100 size 0x79cb
002549.162: brfs: File read: 31179 bytes
002568.470: brfs: File read: /mfs/sd/0123456789012345678901234567890123456789012345678901234567890123/overlays/overlay_map.dtb
002700.593: brfs: File read: 1783 bytes
002709.126: brfs: File read: /mfs/sd/config.txt
002713.633: dtparam: audio=on
002744.989: brfs: File read: 2243 bytes
002754.515: brfs: File read: /mfs/sd/0123456789012345678901234567890123456789012345678901234567890123/cmdline.txt
002764.168: Read command line from file '0123456789012345678901234567890123456789012345678901234567890123/cmdline.txt':
002775.670: 'console=serial0,115200 console=tty1 root=PARTUUID=ae7b131e-02 rootfstype=ext4 fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles'
003343.709: brfs: File read: 148 bytes
003805.451: brfs: File read: /mfs/sd/0123456789012345678901234567890123456789012345678901234567890123/kernel7.img
003815.049: Loading '0123456789012345678901234567890123456789012345678901234567890123/kernel7.img' to 0x8000 size 0x64ae60
003826.859: Device tree loaded to 0x2eff8000 (size 0x7f9e)
...

alfonsosanchezbeato · 2022-04-13T11:33:22Z

To me, 64 max for os_prefix sounds reasonable, yes.

pelwell · 2022-04-13T11:51:03Z

Thanks. A patch implementing that change has been merged to our internal software repo, and will be in future firmware builds.

juergh · 2022-04-13T13:32:27Z

002480.057: dtb_file 'bcm2710-rpi-3-b-plus.dtb'
002491.181: dtb_file 'bcm2710-rpi-3-b.dtb'
002502.935: brfs: File read: /mfs/sd/0123456789012345678901234567890123456789012345678901234567890123/bcm2710-rpi-3-b.dtb
002513.247: Loading '0123456789012345678901234567890123456789012345678901234567890123/bcm2710-rpi-3-b.dtb' to 0x100 size 0x79cb

Is this a 3b or 3b+? And curious, how do you account for potentially growing dtb filenames? Can the FW spit out some error if the resulting pathname is too long?

pelwell · 2022-04-13T13:57:11Z

Ah - that was the output from an intermediate version. A build with the final patch says:

001419.659: brfs: File read: /mfs/sd/config.txt
001425.074: brfs: File read: 2243 bytes
001527.408: brfs: File read: /mfs/sd/config.txt
002392.007: gpioman: gpioman_get_pin_num: pin DISPLAY_DSI_PORT not defined
002399.631: gpioman: gpioman_get_pin_num: pin EMMC_ENABLE not defined
002406.721: *** Restart logging
002409.352: brfs: File read: 2243 bytes
002450.354: HDMI0: hdmi_pixel_encoding: 162000000
002479.581: dtb_file 'bcm2710-rpi-3-b-plus.dtb'
002494.141: brfs: File read: /mfs/sd/0123456789012345678901234567890123456789012345678901234567890123/bcm2710-rpi-3-b-plus.dtb
002504.892: Loading '0123456789012345678901234567890123456789012345678901234567890123/bcm2710-rpi-3-b-plus.dtb' to 0x100 size 0x7c2e
002541.653: brfs: File read: 31790 bytes
002560.996: brfs: File read: /mfs/sd/0123456789012345678901234567890123456789012345678901234567890123/overlays/overlay_map.dtb
002695.569: brfs: File read: 1783 bytes
002704.099: brfs: File read: /mfs/sd/config.txt
002708.607: dtparam: audio=on
002740.680: brfs: File read: 2243 bytes
002750.312: brfs: File read: /mfs/sd/0123456789012345678901234567890123456789012345678901234567890123/cmdline.txt
002759.965: Read command line from file '0123456789012345678901234567890123456789012345678901234567890123/cmdline.txt':
002771.466: 'console=serial0,115200 console=tty1 root=PARTUUID=ae7b131e-02 rootfstype=ext4 fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles'
003351.952: brfs: File read: 148 bytes
003813.461: brfs: File read: /mfs/sd/0123456789012345678901234567890123456789012345678901234567890123/kernel7.img
003823.059: Loading '0123456789012345678901234567890123456789012345678901234567890123/kernel7.img' to 0x8000 size 0x64ae60
003834.869: Device tree loaded to 0x2eff7d00 (size 0x8201)
...

how do you account for potentially growing dtb filenames?

The internal limit has been raised by 64 bytes, all of which are notionally given to os_prefix. This will leave enough headroom for an overlay name to be longer than the current champion by 7-8 bytes.

Can the FW spit out some error if the resulting pathname is too long?

That would be a more invasive change than I would like.

See: raspberrypi/linux#4983 kernel: vc4_hdmi: Remove VC4_HDMI_SCHEDULER_CONTROL_VERT_ALWAYS_KEEPOUT See: raspberrypi/linux#4972 firmware: arm_loader: Support longer file paths See: #1720

See: raspberrypi/linux#4983 kernel: vc4_hdmi: Remove VC4_HDMI_SCHEDULER_CONTROL_VERT_ALWAYS_KEEPOUT See: raspberrypi/linux#4972 firmware: arm_loader: Support longer file paths See: raspberrypi/firmware#1720

popcornmix · 2022-04-13T14:19:27Z

Updated firmware with increased os_prefix length is available from rpi-update

alfonsosanchezbeato · 2022-04-18T09:27:52Z

I have checked that with latest firmware in master (4fe2e4a) things work as expected and my RPi3b+ is detected properly while having the relatively long os_prefix=/piboot/ubuntu/pi-kernel_x1.snap/. Thanks a lot!

pelwell closed this as completed Apr 18, 2022

macmpi mentioned this issue Dec 30, 2022

Regression post 1.20220331: blk_update_request: I/O error, dev sr0 #1765

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RPi3b+ boards are detected as RPi3b when using os_prefix option #1720

RPi3b+ boards are detected as RPi3b when using os_prefix option #1720

alfonsosanchezbeato commented Apr 11, 2022 •

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RPi3b+ boards are detected as RPi3b when using os_prefix option #1720

RPi3b+ boards are detected as RPi3b when using os_prefix option #1720

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