Full output:

/usr/bin/qemu-system-arm \
    -global virtio-blk-device.scsi=off \
    -no-user-config \
    -enable-fips \
    -nodefaults \
    -display none \
    -machine virt,accel=kvm:tcg \
    -cpu host \
    -m 1280 \
    -no-reboot \
    -rtc driftfix=slew \
    -kernel /var/tmp/.guestfs-1000/appliance.d/kernel \
    -initrd /var/tmp/.guestfs-1000/appliance.d/initrd \
    -object rng-random,filename=/dev/urandom,id=rng0 \
    -device virtio-rng-device,rng=rng0 \
    -device virtio-scsi-device,id=scsi \
    -drive file=nbd:unix:/tmp/nbdkitgtoKeO/socket,cache=writeback,id=hd0,if=none \
    -device scsi-hd,drive=hd0 \
    -drive file=/var/tmp/.guestfs-1000/appliance.d/root,snapshot=on,id=appliance,cache=unsafe,if=none,format=raw \
    -device scsi-hd,drive=appliance \
    -device virtio-serial-device \
    -serial stdio \
    -chardev socket,path=/tmp/libguestfs281W3m/guestfsd.sock,id=channel0 \
    -device virtserialport,chardev=channel0,name=org.libguestfs.channel.0 \
    -append "panic=1 mem=1280M console=ttyAMA0 edd=off udevtimeout=6000 udev.event-timeout=6000 no_timer_check printk.time=1 cgroup_disable=memory usbcore.nousb cryptomgr.notests tsc=reliable 8250.nr_uarts=1 root=UUID=814dcbd6-ef9e-4e9e-9566-36f8bf5d4333 selinux=0 guestfs_verbose=1 TERM=vt100"
qemu-system-arm: /builddir/build/BUILD/qemu-5.1.0/exec.c:1458: phys_section_add: Assertion `map->sections_nb < TARGET_PAGE_SIZE' failed.

Bug also happens on aarch64:

/usr/bin/qemu-system-aarch64 \
    -global virtio-blk-pci.scsi=off \
    -no-user-config \
    -enable-fips \
    -nodefaults \
    -display none \
    -machine virt,gic-version=host,accel=kvm:tcg \
    -cpu host \
    -m 1280 \
    -no-reboot \
    -rtc driftfix=slew \
    -drive if=pflash,format=raw,file=/usr/share/AAVMF/AAVMF_CODE.fd,readonly \
    -drive if=pflash,format=raw,file=/tmp/libguestfs443tL1/vars3.fd \
    -kernel /var/tmp/.guestfs-1000/appliance.d/kernel \
    -initrd /var/tmp/.guestfs-1000/appliance.d/initrd \
    -object rng-random,filename=/dev/urandom,id=rng0 \
    -device virtio-rng-pci,rng=rng0 \
    -device virtio-scsi-pci,id=scsi \
    -drive file=nbd:unix:/tmp/nbdkitMaPlbS/socket,cache=writeback,id=hd0,if=none \
    -device scsi-hd,drive=hd0 \
    -drive file=/var/tmp/.guestfs-1000/appliance.d/root,snapshot=on,id=appliance,cache=unsafe,if=none,format=raw \
    -device scsi-hd,drive=appliance \
    -device virtio-serial-pci \
    -serial stdio \
    -chardev socket,path=/tmp/libguestfsWTWpz4/guestfsd.sock,id=channel0 \
    -device virtserialport,chardev=channel0,name=org.libguestfs.channel.0 \
    -append "panic=1 console=ttyAMA0 earlyprintk=pl011,,0x9000000 ignore_loglevel efi-rtc=noprobe edd=off udevtimeout=6000 udev.event-timeout=6000 no_timer_check printk.time=1 cgroup_disable=memory usbcore.nousb cryptomgr.notests tsc=reliable 8250.nr_uarts=1 root=UUID=f8570e82-5b99-48bb-b52e-74587d187cc5 selinux=0 guestfs_verbose=1 TERM=vt100"
qemu-system-aarch64: /builddir/build/BUILD/qemu-5.1.0/exec.c:1458: phys_section_add: Assertion `map->sections_nb < TARGET_PAGE_SIZE' failed.

This is the shortest reproducer I could make:

$ qemu-system-aarch64 -machine virt,accel=kvm:tcg -m 1280 
qemu-system-aarch64: /builddir/build/BUILD/qemu-5.1.0/exec.c:1458: phys_section_add: Assertion `map->sections_nb < TARGET_PAGE_SIZE' failed.

For unclear reasons it only crashes with qemu from Fedora Rawhide, not
with qemu that I built myself from git.

Stack trace from the assert fail:

#0  0x0000ffff9bc68630 in raise () at /lib64/libc.so.6
#1  0x0000ffff9bc5481c in abort () at /lib64/libc.so.6
#2  0x0000ffff9bc6176c in __assert_fail_base () at /lib64/libc.so.6
#3  0x0000ffff9bc617d4 in annobin_assert.c_end () at /lib64/libc.so.6
#4  0x0000aaaab3b6ac50 in phys_section_add
    (map=<optimized out>, section=section@entry=0xffffe0c48fc0)
    at /usr/src/debug/qemu-5.1.0-6.fc34.aarch64/exec.c:1458
#5  0x0000aaaab3b6bb2c in dummy_section
    (mr=0xaaaab4879d10 <io_mem_unassigned>, fv=0xaaaaef383d00, map=<optimized out>) at /usr/src/debug/qemu-5.1.0-6.fc34.aarch64/exec.c:2931
#6  address_space_dispatch_new (fv=0xaaaaef383d00)
    at /usr/src/debug/qemu-5.1.0-6.fc34.aarch64/exec.c:2931
#7  0x0000aaaab3cf7514 in generate_memory_topology (mr=mr@entry=0x0)
    at /usr/src/debug/qemu-5.1.0-6.fc34.aarch64/softmmu/memory.c:717
#8  0x0000aaaab3cf780c in flatviews_init ()
    at /usr/src/debug/qemu-5.1.0-6.fc34.aarch64/softmmu/memory.c:970
#9  flatviews_init ()
    at /usr/src/debug/qemu-5.1.0-6.fc34.aarch64/softmmu/memory.c:959
#10 0x0000aaaab3cf7b08 in address_space_update_topology
    (as=0xaaaab4879eb8 <address_space_memory>)
    at /usr/src/debug/qemu-5.1.0-6.fc34.aarch64/softmmu/memory.c:1050
#11 address_space_init
    (as=0xaaaab4879eb8 <address_space_memory>, root=<optimized out>, name=0xaaaab436e220 "memory")
    at /usr/src/debug/qemu-5.1.0-6.fc34.aarch64/softmmu/memory.c:2772
#12 0x0000aaaab3b6eb60 in memory_map_init ()
    at /usr/src/debug/qemu-5.1.0-6.fc34.aarch64/exec.c:3007
#13 cpu_exec_init_all ()
    at /usr/src/debug/qemu-5.1.0-6.fc34.aarch64/exec.c:3463
#14 0x0000aaaab3d068a0 in qemu_init
    (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>)
    at /usr/src/debug/qemu-5.1.0-6.fc34.aarch64/softmmu/vl.c:3901
#15 0x0000aaaab3b67a50 in main
    (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>)
    at /usr/src/debug/qemu-5.1.0-6.fc34.aarch64/softmmu/main.c:48

This is caused by enabling LTO.

While this is fixed in qemu-5.1.0-8.fc33.aarch64 I'm not sure
if we want to close this bug yet.  The bug was caused by LTO,
and to "fix" it we just turned LTO off.

This bug appears to have been reported against 'rawhide' during the Fedora 34 development cycle.
Changing version to 34.