clone https://github.com/raspberrypi/usbboot $ cd usbboot $ make $ sudo ./rpiboot raspberrypi/usbboot: Raspberry Pi USB booting code, moved from tools repository 11 / 27
2022 version 20220504~214218 5e0ae34d Waiting for BCM2835/6/7/2711... Loading embedded: bootcode.bin Sending bootcode.bin Successful read 4 bytes Waiting for BCM2835/6/7/2711... Loading embedded: bootcode.bin Second stage boot server Loading embedded: start.elf File read: start.elf Second stage boot server done [ +0.000798] usb 2-2: New USB device found, idVendor=0a5c, idProduct=2764, bcdDevice= 0.00 [ +0.000014] usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=1 [ +0.000007] usb 2-2: Product: BCM2710 Boot [ +0.000005] usb 2-2: Manufacturer: Broadcom [ +0.000005] usb 2-2: SerialNumber: Broadcom [May13 23:02] usb 2-2: USB disconnect, device number 124 12 / 27
a ramdisk file is 96MB. Buildroot - Making Embedded Linux Easy https://www.raspberrypi.com/documentation/compute pi.html#configuration-properties-in-config-txt 15 / 27
$ wget2 https://github.com/pweaver/buildroot/raw/master/buildroot_pubkey.gpg $ gpg --import ./buildroot_pubkey.gpg gpg: /home/ubuntu/.gnupg/trustdb.gpg: trustdb created gpg: key B025BA8B59C36319: public key "Peter Korsgaard <[email protected]>" imported gpg: Total number processed: 1 gpg: imported: 1 $ gpg --verify ./buildroot-2022.02.1.tar.xz.sign gpg: Signature made Mon 11 Apr 2022 09:51:18 PM UTC gpg: using DSA key AB07D806D2CE741FB886EE50B025BA8B59C36319 gpg: Good signature from "Peter Korsgaard <[email protected]>" [unknown] gpg: WARNING: This key is not certified with a trusted signature! gpg: There is no indication that the signature belongs to the owner. Primary key fingerprint: AB07 D806 D2CE 741F B886 EE50 B025 BA8B 59C3 6319 gpg: WARNING: not a detached signature; file './buildroot-2022.02.1.tar.xz' was NOT verified! $ tar tvf ./buildroot-2022.02.1.tar.xz | lv $ tar xf ./buildroot-2022.02.1.tar.xz $ cd buildroot-2022.02.1 16 / 27
linked into linux kernel (BR2_TARGET_ROOTFS_INITRAMFS) cpio the root filesystem (for use as an initial RAM filesystem) (BR2_TARGET_ROOTFS_CPIO) xz (BR2_TARGET_ROOTFS_CPIO_XZ) $ time make -j$( nproc ) 21 / 27