This changes add - kernel_comp_addr_r=0x0800000 - kernel_comp_size=0x0800000 to the default environment of the raspberry pi. With these two options u-boot can uncompress a received compressed kernel and boot it.
I could just test these changes on raspberry pi 4B with 8GB of ram.
See the attached logs.
U-Boot 2021.10-dirty (Jan 08 2022 - 05:57:42 +0100)
DRAM: 7.9 GiB RPI 4 Model B (0xd03114) MMC: mmc@7e300000: 0, mmc@7e340000: 1 Loading Environment from FAT... Card did not respond to voltage select! : -110 In: serial Out: vidconsole Err: vidconsole Net: eth0: ethernet@7d580000 PCIe BRCM: link up, 5.0 Gbps x1 (SSC) starting USB... Bus usb@7e980000: USB DWC2 Bus xhci_pci: Register 5000420 NbrPorts 5 Starting the controller USB XHCI 1.00 scanning bus usb@7e980000 for devices... 1 USB Device(s) found scanning bus xhci_pci for devices... Failed to get keyboard state from device 1997:2433 2 USB Device(s) found scanning usb for storage devices... 0 Storage Device(s) found Hit any key to stop autoboot: 0 U-Boot> setenv boot_targets "dhcp pxe" U-Boot> boot
georg@rpi64-test:~$ dmesg [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd083] [ 0.000000] Linux version 5.15.10-rt24-v8 (georg@hammerhead) (aarch64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2) #1 SMP PREEMPT_RT Wed Jan 5 21:06:46 CET 2022 [ 0.000000] Machine model: Raspberry Pi 4 Model B Rev 1.4 [ 0.000000] efi: UEFI not found. [ 0.000000] Reserved memory: created CMA memory pool at 0x0000000037400000, size 64 MiB [ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool [ 0.000000] Zone ranges: [ 0.000000] DMA [mem 0x0000000000000000-0x000000003fffffff] [ 0.000000] DMA32 [mem 0x0000000040000000-0x00000000ffffffff] [ 0.000000] Normal [mem 0x0000000100000000-0x00000001ffffffff] [ 0.000000] Movable zone start for each node [ 0.000000] Early memory node ranges [ 0.000000] node 0: [mem 0x0000000000000000-0x000000003b3fffff] [ 0.000000] node 0: [mem 0x0000000040000000-0x00000000fbffffff] [ 0.000000] node 0: [mem 0x0000000100000000-0x00000001ffffffff] [ 0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x00000001ffffffff] [ 0.000000] percpu: Embedded 27 pages/cpu s73392 r8192 d29008 u110592 [ 0.000000] pcpu-alloc: s73392 r8192 d29008 u110592 alloc=27*4096 [ 0.000000] pcpu-alloc: [0] 0 [0] 1 [0] 2 [0] 3 [ 0.000000] Detected PIPT I-cache on CPU0 [ 0.000000] CPU features: detected: Spectre-v2 [ 0.000000] CPU features: detected: Spectre-v4 [ 0.000000] CPU features: detected: ARM errata 1165522, 1319367, or 1530923 [ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 2028848 [ 0.000000] Kernel command line: rw console=ttyAMA0,115200u8 console=tty1 earlyprintk root=/dev/nfs nfsroot=192.168.160.19:/srv/netboot/rpi64/rootfs ip=192.168.160.42:192.168.160.19:192.168.160.1::rpi64-test.schorsch-tech.de nfsrootdebug [ 0.000000] Unknown kernel command line parameters "earlyprintk nfsrootdebug", will be passed to user space.