[9front] 9front on rpi4 rev 1.4

[9front] 9front on rpi4 rev 1.4

[k.st]

I recently acquired a new 2GB raspberry pi 4, tried to run
the 9front pi3 image on it, and got the exact same

    sdhc: readerror intr 2008002 stat 1fff0000

error as mentioned in [1]. Strangely, the image works fine
on an old 4GB rpi 4 I have.

I don't think the memory difference matters here. The only
other difference I could notice is the "revision number" of
the two devices. The old rpi4 (working) is revision 1.2,

    linux$ cat /proc/cpuinfo
    processor	: 0
    model name	: ARMv7 Processor rev 3 (v7l)
    BogoMIPS	: 108.00
    Features	: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
    CPU implementer	: 0x41
    CPU architecture: 7
    CPU variant	: 0x0
    CPU part	: 0xd08
    CPU revision	: 3

    processor	: 1
    model name	: ARMv7 Processor rev 3 (v7l)
    BogoMIPS	: 108.00
    Features	: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
    CPU implementer	: 0x41
    CPU architecture: 7
    CPU variant	: 0x0
    CPU part	: 0xd08
    CPU revision	: 3

    processor	: 2
    model name	: ARMv7 Processor rev 3 (v7l)
    BogoMIPS	: 108.00
    Features	: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
    CPU implementer	: 0x41
    CPU architecture: 7
    CPU variant	: 0x0
    CPU part	: 0xd08
    CPU revision	: 3

    processor	: 3
    model name	: ARMv7 Processor rev 3 (v7l)
    BogoMIPS	: 108.00
    Features	: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
    CPU implementer	: 0x41
    CPU architecture: 7
    CPU variant	: 0x0
    CPU part	: 0xd08
    CPU revision	: 3

    Hardware	: BCM2711
    Revision	: c03112
    Serial		: [REDACTED]
    Model		: Raspberry Pi 4 Model B Rev 1.2

while the new model (not working) is revision 1.4

    linux$ cat /proc/cpuinfo
    processor	: 0
    model name	: ARMv7 Processor rev 3 (v7l)
    BogoMIPS	: 126.00
    Features	: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
    CPU implementer	: 0x41
    CPU architecture: 7
    CPU variant	: 0x0
    CPU part	: 0xd08
    CPU revision	: 3

    processor	: 1
    model name	: ARMv7 Processor rev 3 (v7l)
    BogoMIPS	: 126.00
    Features	: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
    CPU implementer	: 0x41
    CPU architecture: 7
    CPU variant	: 0x0
    CPU part	: 0xd08
    CPU revision	: 3

    processor	: 2
    model name	: ARMv7 Processor rev 3 (v7l)
    BogoMIPS	: 126.00
    Features	: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
    CPU implementer	: 0x41
    CPU architecture: 7
    CPU variant	: 0x0
    CPU part	: 0xd08
    CPU revision	: 3

    processor	: 3
    model name	: ARMv7 Processor rev 3 (v7l)
    BogoMIPS	: 126.00
    Features	: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
    CPU implementer	: 0x41
    CPU architecture: 7
    CPU variant	: 0x0
    CPU part	: 0xd08
    CPU revision	: 3

    Hardware	: BCM2711
    Revision	: b03114
    Serial		: [REDACTED]
    Model		: Raspberry Pi 4 Model B Rev 1.4

I'm not sure about the exact hardware difference between the
two revisions, though one thing I notice is that the older
model seems to have a dedicated EEPROM for VL805 USB firmware

    linux$ sudo rpi-eeprom-update
    *** UPDATE AVAILABLE ***
    BOOTLOADER: update available
       CURRENT: Thu 03 Sep 2020 12:11:43 PM UTC (1599135103)
        LATEST: Thu 29 Apr 2021 04:11:25 PM UTC (1619712685)
       RELEASE: default (/lib/firmware/raspberrypi/bootloader/default)
                Use raspi-config to change the release.

      VL805_FW: Dedicated VL805 EEPROM
         VL805: up to date
       CURRENT: 000138a1
        LATEST: 000138a1

while the newer model doesn't:

    linux$ sudo rpi-eeprom-update
    *** UPDATE AVAILABLE ***
    BOOTLOADER: update available
       CURRENT: Tue 16 Feb 2021 01:23:36 PM UTC (1613481816)
        LATEST: Thu 29 Apr 2021 04:11:25 PM UTC (1619712685)
       RELEASE: default (/lib/firmware/raspberrypi/bootloader/default)
                Use raspi-config to change the release.

      VL805_FW: Using bootloader EEPROM
         VL805: up to date
       CURRENT: 000138a1
        LATEST: 000138a1

I'm not sure how this affects the booting of 9front. I can
confirm the firmware difference doesn't matter. I downgraded
the newer model's firmware to 03 Sep 2020, still got the
same error.

However, Richard Miller's 9pi image does work on the newer
model. Maybe something needs to be backported to 9front.

I also tried to boot freebsd on this newer model of rpi4 and
ran into a similar issue (works on old model, doesn't work
on new model). There are some discussions on the freebsd
forum that might be related

- https://forums.freebsd.org/threads/stuck-in-u-boot-during-freebsd-13-install-on-raspberry-pi-400.79941/
- https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=255080

The fix proposed in [2] works, but it doesn't apply to
9front.

Does anyone have any successes with booting 9front on a rpi4
rev 1.4?

- kst

[1]: https://inbox.vuxu.org/9front/0100017720d2f6b4-a93bc058-3523-49a3-99c9-41d030c74716-000000@email.amazonses.com/T/#u
[2]: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=255080#c15