This is a follow up to a previous question (u-boot: cannot boot linux kernel despite kernel being less than maximum BOOTM_LEN) on the same platform (MIPS VSC7427).
I am trying to boot Linux 5.11 and u-boot hangs at "Uncompressing Kernel Image" (gzip compression):
U-Boot 2019.10 (Mar 28 2021 - 20:41:55 +0000)
MSCC VCore-III MIPS 24Kec
Model: Cisco Meraki MS220-8P
DRAM: 128 MiB
Loading Environment from SPI Flash... SF: Detected mx25l12805d with page size 256 Bytes, erase size 64 KiB, total 16 MiB
OK
In: serial@10100000
Out: serial@10100000
Err: serial@10100000
Net:
Warning: switch@1010000 (eth0) using random MAC address - f6:22:ff:96:01:2d
eth0: switch@1010000
luton # setenv loadaddr 0x83000000
luton # dhcp
luton # tftp ${loadaddr} vmlinux.gz.itb
Using switch@1010000 device
TFTP from server 192.168.1.60; our IP address is 192.168.1.164
Filename 'vmlinux.gz.itb'.
Load address: 0x83000000
Loading: #################################################################
(snipped)
done
Bytes transferred = 5172240 (4eec10 hex)
luton # bootm 0x83000000
## Loading kernel from FIT Image at 83000000 ...
Using 'conf@default' configuration
Trying 'kernel@0' kernel subimage
Description: Linux 5.11.11
Type: Kernel Image
Compression: gzip compressed
Data Start: 0x830000c0
Data Size: 5167511 Bytes = 4.9 MiB
Architecture: MIPS
OS: Linux
Load Address: 0x80100000
Entry Point: 0x809898f4
Hash algo: sha1
Hash value: b963ed48f45e332bd5df263dd69d69c3818e6586
Verifying Hash Integrity ... sha1+ OK
Uncompressing Kernel Image
Trying to boot an uncompressed vmlinux results in u-boot hanging at "Loading Kernel Image":
luton # setenv loadaddr 0x83000000
luton # setenv fdtaddr 0x85000000
luton # dhcp
luton # tftp ${loadaddr} vmlinux.bin
luton # tftp ${fdtaddr} ms220.dtb
luton # bootm ${loadaddr} - ${fdtaddr}
## Booting kernel from Legacy Image at 83000000 ...
Image Name: Linux 5.11.11
Image Type: MIPS Linux Kernel Image (uncompressed)
Data Size: 11531664 Bytes = 11 MiB
Load Address: 80100000
Entry Point: 809898f4
Verifying Checksum ... OK
## Flattened Device Tree blob at 85000000
Booting using the fdt blob at 0x85000000
Loading Kernel Image
I have looked at other questions regarding u-boot hanging at "Loading Kernel Image" and I don't believe the suggestions there (reading from addresses not in DRAM) apply to my situation.
The Kernel Load Address of 0x80100000 corresponds to CONFIG_SYS_SDRAM_BASE + CONFIG_SYS_LOAD_ADDR defined in u-boot, so I'm fairly certain I am loading from an address in RAM.
Using the same version of u-boot (2019.10) I am able to boot the 3.18.123 kernel built from the vendor's GPL source:
luton # tftpboot vmlinuz
Using switch@1010000 device
TFTP from server 192.168.1.60; our IP address is 192.168.1.157
Filename 'vmlinuz'.
Load address: 0x81000000
Loading: #################################################################
(snipped)
done
Bytes transferred = 1578176 (1814c0 hex)
luton # bootm ${load_addr}
## Booting kernel from Legacy Image at 81000000 ...
Image Name: Linux 3.18.123
Image Type: MIPS Linux Kernel Image (uncompressed)
Data Size: 1578112 Bytes = 1.5 MiB
Load Address: 81000000
Entry Point: 81000000
Verifying Checksum ... OK
Loading Kernel Image
[ 0.000000] Linux version 3.18.123-meraki-elemental (hmartin@alp) (gcc version 5.4.0 (GCC) ) #36 Tue Apr 14 20:11:18 UTC 2020
(I seem to recall needing to change the Kernel Load Address from 0x80100000 to 0x81000000 for in-kernel decompression to work, but otherwise it boots just fine)
The its file used to generate the FIT image for kernel 5.11.11:
/* SPDX-License-Identifier: GPL-2.0 */
/dts-v1/;
/ {
description = "Linux 5.11.11";
#address-cells = <1>;
images {
kernel@0 {
description = "Linux 5.11.11";
data = /incbin/("vmlinux.bin.gz");
type = "kernel";
arch = "mips";
os = "linux";
compression = "gzip";
load = /bits/ 32 <0xffffffff80100000>;
entry = /bits/ 32 <0xffffffff809898f4>;
hash@0 {
algo = "sha1";
};
};
};
configurations {
default = "conf@default";
conf@default {
description = "Generic Linux kernel";
kernel = "kernel@0";
};
};
};
/* SPDX-License-Identifier: (GPL-2.0 OR MIT) */
/ {
images {
fdt@luton_pcb091 {
description = "MSCC Luton PCB091 Device Tree";
data = /incbin/("boot/dts/mscc/luton_pcb091.dtb");
type = "flat_dt";
arch = "mips";
compression = "none";
hash@0 {
algo = "sha1";
};
};
};
configurations {
pcb091 {
description = "Luton Linux kernel";
kernel = "kernel@0";
fdt = "fdt@luton_pcb091";
};
};
};
Trying either of the following earlycon boot arguments has zero effect:
luton # setenv bootargs console=ttyS0,115200 earlycon=uart,mmio,0x10100000 mem=134152192
luton # setenv bootargs console=ttyS0,115200 earlycon=uart,mmio,0x70100000 mem=134152192
(0x10100000 is the uart offset in the ahb section of the kernel dts and in u-boot, 0x70100000 is the UART base address used in the vendor kernel)
The mkimage command used to generate the uncompressed 5.11 kernel image:
mkimage -A mips -O linux -T kernel -C none -a 0x80100000 -e $(readelf -h vmlinux | grep "Entry point address" | awk '{print $4}') -n "Linux 5.11.11" -d arch/mips/boot/vmlinux.bin /var/lib/tftpboot/vmlinux.bin
mkimage version 2020.01
