Raspberry Pi Install Guide/Exposing the eMMC

Exposing Compute Module eMMC

Fit jumper to disable eMMC boot.

The Raspberry Pi utility usbboot is required. It's not yet packaged for Gentoo, so do it the hard way

~git clone --depth=1 https://github.com/raspberrypi/usbboot

~cd usbboot

~/usbboot make

Warning
The default make install installs to the root filesystem as owned by portage, rather than /usr/local

Take care to set the INSTALL_PREFIX.

~/usbbootsudo INSTALL_PREFIX="/usr/local" make install

install -m 755 rpiboot /usr/local/bin/
install -d /usr/local/share/rpiboot
install -d /usr/local/share/rpiboot/msd
install -d /usr/local/share/rpiboot/mass-storage-gadget64
install -m 644 msd/bootcode.bin  /usr/local/share/rpiboot/msd
install -m 644 msd/bootcode4.bin /usr/local/share/rpiboot/msd
install -m 644 msd/start.elf  /usr/local/share/rpiboot/msd
install -m 644 msd/start4.elf /usr/local/share/rpiboot/msd
install -m 644 mass-storage-gadget64/boot.img /usr/local/share/rpiboot/mass-storage-gadget64
install -m 644 mass-storage-gadget64/config.txt /usr/local/share/rpiboot/mass-storage-gadget64
install -m 644 mass-storage-gadget64/bootfiles.bin /usr/local/share/rpiboot/mass-storage-gadget64

Power up the Pi using a USB data port from a PC or USB hub. On the CM5 tested, the PSU load was under 400mA.

user $sudo ./rpiboot -d /usr/local/share/rpiboot/mass-storage-gadget64

RPIBOOT: build-date Jan  2 2025 version 20240422~085300 ef721cda
If the device fails to connect then please see https://rpltd.co/rpiboot for debugging tips.
Loading: /usr/local/share/rpiboot/mass-storage-gadget64/bootfiles.bin
Using /usr/local/share/rpiboot/mass-storage-gadget64/bootfiles.bin
Waiting for BCM2835/6/7/2711/2712...
Sending bootcode.bin
Successful read 4 bytes 
Waiting for BCM2835/6/7/2711/2712...
Second stage boot server
File read: mcb.bin
File read: memsys00.bin
File read: memsys01.bin
File read: memsys02.bin
File read: memsys03.bin
File read: bootmain
Loading: /usr/local/share/rpiboot/mass-storage-gadget64/config.txt
File read: config.txt
Loading: /usr/local/share/rpiboot/mass-storage-gadget64/boot.img
File read: boot.img
Second stage boot server done

Will load the boot code over USB using the mass-storage-gadget64, then expose the eMMC as a USB storage device over the USB2 provided in the power connector.

user $sudo ./rpiboot -d /usr/local/share/rpiboot/mass-storage-gadget64

must be used every time that USB Mass Storage mode is required.

Other payloads can also be booted this way. See ./Readme.md

Testing

Inspect the end of the output of dmesg

user $dmesg

...
[10096.645486] usb 1-4.2: new high-speed USB device number 11 using xhci_hcd
[10096.740158] usb 1-4.2: New USB device found, idVendor=0a5c, idProduct=0104, bcdDevice= 1.00
[10096.740165] usb 1-4.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[10096.740168] usb 1-4.2: Product: Raspberry Pi multi-function USB device
[10096.740170] usb 1-4.2: Manufacturer: Raspberry Pi
[10096.740172] usb 1-4.2: SerialNumber: c8dee776c5ff72a0
[10096.794078] usb-storage 1-4.2:1.0: USB Mass Storage device detected
[10096.794306] scsi host10: usb-storage 1-4.2:1.0
[10097.805288] scsi 10:0:0:0: Direct-Access     mmcblk0                        PQ: 0 ANSI: 2
[10097.805405] scsi 10:0:0:0: Attached scsi generic sg6 type 0
[10097.805680] sd 10:0:0:0: Power-on or device reset occurred
[10097.806636] sd 10:0:0:0: [sde] 61071360 512-byte logical blocks: (31.3 GB/29.1 GiB)
[10097.943867] sd 10:0:0:0: [sde] Write Protect is off
[10097.943874] sd 10:0:0:0: [sde] Mode Sense: 0f 00 00 00
[10098.079880] sd 10:0:0:0: [sde] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[10098.373702] sd 10:0:0:0: [sde] Attached SCSI removable disk

The partitioning tool of your choice can be used on /dev/sde, from the example dmesg output above.

root #fdisk -l /dev/sde Disk /dev/sde: 29.12 GiB, 31268536320 bytes, 61071360 sectors

root #Disk model:

root #Units: sectors of 1 * 512 = 512 bytes

root #Sector size (logical/physical): 512 bytes / 512 bytes

root #I/O size (minimum/optimal): 512 bytes / 512 bytes

Installing

Follow the rest of this guide, then come back here

Important
When the install is complete, remove the jumper or the CM will not boot