So I followed the instructions here:
https://documentation.suse.com/fr-fr/sles/12-SP3/html/SLES-all/cha-tuning-kexec.html#cha-tuning-kexec-basic-usage,
below the output on an Unmatched board using a vmlinux stored on a sd
card:
ubuntu@ubuntu:~$ sudo sbin/kexec -l vmlinux --append="$(cat
/proc/cmdline)" --initrd=/boot/initrd.img
Warning: No cmdline provided, using append string as cmdline
Warning: No dtb provided, using /sys/firmware/fdt
[ 1813.472671] INFO: task kworker/1:0:988 blocked for more than 120 seconds.
[ 1813.478751] Not tainted 5.15.0-rc1+ #15
[ 1813.483110] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
Could not find a free area of memory of 0x3000 bytes...
locate_hole failed
I used the Ubuntu kernel, so this is pretty large:
-rwxrwxr-x 1 ubuntu ubuntu 277M Oct 5 15:47 vmlinux
-rw-r--r-- 1 root root 98M Sep 21 03:25 /boot/initrd.img
Then if I don't load the initrd (I sometimes have the same warning as
above) I can at least kexec the new kernel but it fails to boot:
ubuntu@ubuntu:~$ sudo ./sbin/kexec -e
Warning: No cmdline or append string provided
Warning: No dtb provided, using /sys/firmware/fdt
[...]
[ 0.000000] SBI v0.2 HSM extension detected
[ 0.000000] CPU with hartid=0 is not available
[ 0.000000] ------------[ cut here ]------------
[ 0.000000] kernel BUG at arch/riscv/kernel/smpboot.c:107!
[ 0.000000] Kernel BUG [#1]
[ 0.000000] Modules linked in:
[ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.15.0-rc1+ #15
[ 0.000000] Hardware name: SiFive HiFive Unmatched A00 (DT)
[ 0.000000] epc : setup_smp+0xcc/0x142
[ 0.000000] ra : setup_smp+0xc4/0x142
[ 0.000000] epc : ffffffff80a04080 ra : ffffffff80a04078 sp :
ffffffff81803ec0
[ 0.000000] gp : ffffffff81a23220 tp : ffffffff81810500 t0 :
ffffffff81a3551f
[ 0.000000] t1 : ffffffffffffffff t2 : 0000000000000000 s0 :
ffffffff81803f00
[ 0.000000] s1 : 0000000000000000 a0 : 0000000000000000 a1 :
0000000000000000
[ 0.000000] a2 : 0000000000000000 a3 : 0000000000000001 a4 :
0000000000000000
[ 0.000000] a5 : ffffffff80c64500 a6 : 0000000000000004 a7 :
000000000000ff00
[ 0.000000] s2 : 0000000000000005 s3 : 0000000000000000 s4 :
ffffffff8118f9a8
[ 0.000000] s5 : 0000000000000007 s6 : ffffffff80c0b790 s7 :
0000000080000200
[ 0.000000] s8 : 0000000000000fff s9 : 0000000081000200 s10:
0000000000000018
[ 0.000000] s11: 000000000000000b t3 : 0000000000ff0000 t4 :
ffffffffffffffff
[ 0.000000] t5 : ffffffff80c0b7a0 t6 : ffffffff81803bd8
[ 0.000000] status: 0000000200000100 badaddr: 0000000000000000
cause: 0000000000000003
[ 0.000000] [<ffffffff80a04080>] setup_smp+0xcc/0x142
[ 0.000000] [<ffffffff80a03d88>] setup_arch+0x56a/0x590
[ 0.000000] [<ffffffff80a00aa2>] start_kernel+0xaa/0xa5c
[ 0.000000] random: get_random_bytes called from
oops_exit+0x44/0x70 with crng_init=0
[ 0.000000] ---[ end trace 0000000000000000 ]---
[ 0.000000] Kernel panic - not syncing: Attempted to kill the idle task!
[ 0.000000] ---[ end Kernel panic - not syncing: Attempted to kill
the idle task! ]---
This reliably fails here.