Well, here's one situation where "fastboot boot image" doesn't work.
If you are trying to check a recovery by "fastboot boot image" the system doesn't know offhand that it is a recovery.
A bunch of parameters are attached to the image by the cmdline (you can see this by "imgutil.exe /v image"):
Code:
console=ttyMSM0,115200,n8 androidboot.console=ttyMSM0 earlycon=msm_serial_dm,0xc170000 androidboot.hardware=qcom user_debug=31 msm_rtb.filter=0x37 ehci-hcd.park=3 lpm_levels.sleep_disabled=1 sched_enable_hmp=1 sched_enable_power_aware=1 service_locator.enable=1 swiotlb=1 loop.max_part=7 buildvariant=user veritykeyid=id:7e4333f9bba00adfe0ede979e28ed1920492b40
But, when the image gets started the system throws in a bunch more extra parameters (you can see this by "cat /proc/cmdline"):
Code:
rcupdate.rcu_expedited=1 console=ttyMSM0,115200,n8 androidboot.console=ttyMSM0 earlycon=msm_serial_dm,0xc170000 androidboot.hardware=qcom user_debug=31 msm_rtb.filter=0x37 ehci-hcd.park=3 lpm_levels.sleep_disabled=1 sched_enable_hmp=1 sched_enable_power_aware=1 service_locator.enable=1 swiotlb=1 loop.max_part=7 buildvariant=user androidboot.selinux=permissive veritykeyid=id:7e4333f9bba00adfe0ede979e28ed1920492b40f root=/dev/dm-0 dm="system none ro,0 1 android-verity /dev/mmcblk0p10" androidboot.verifiedbootstate=orange androidboot.keymaster=1 androidboot.veritymode=logging androidboot.bootdevice=c0c4000.sdhci androidboot.serialno=12345678 androidboot.mode=recovery androidboot.baseband=apq mdss_mdp.panel=1:dsi:0:qcom,mdss_dsi_nt35695b_truly_fhd_cmd:config0:1:none:cfg:single_dsi rootwait ro init=/init androidboot.dtb_idx=-1347440721 pcb_version=0
This is a difference of 393 vs 858 characters.
If you try to "fastboot boot image" a recovery it will be missing the flag "androidboot.mode=recovery" and it will fail.
The kernel is the same in boot and recovery and it has to know what it is.
Usually this should work for regular (non-recovery) images.
I just tried "fastboot boot image" of my regular image and it worked fine.
Still, there is more unresolved mystery in all this.
Edit: Did you check your Magisk'ed image with imgutil.exe /v?
Edit^2: The DTB on boot_a is really screwed up. Which boot image did you start with?
Edit^3: Ok, it's only a secondary DTB for RTIC (RealTime Integrity Check). I ain't ever heard of that; they're always throwing new stuff at us.