[HTC U12+ Guides, News, & Discussion] goodman_east:
HTC U12+ is an A-B slot phone. There is no recovery partition, but it has boot_a and boot_b partitions, so it CAN boot to recovery mode.

Here is the partitions table from Chinese HTC U12+

lrwxrwxrwx 1 root root 15 1970-01-30 10:42 abl_a -> /dev/block/sde9
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 abl_b -> /dev/block/sde30
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 aop_a -> /dev/block/sde1
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 aop_b -> /dev/block/sde22
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 apdp -> /dev/block/sde46
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 avb_rec -> /dev/block/sde56
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 bluetooth_a -> /dev/block/sde6
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 bluetooth_b -> /dev/block/sde27
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 board_info -> /dev/block/sdf1
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 boot_a -> /dev/block/sde13
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 boot_b -> /dev/block/sde34
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 carrier -> /dev/block/sda16
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 cdt -> /dev/block/sdd2
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 cmnlib64_a -> /dev/block/sde16
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 cmnlib64_b -> /dev/block/sde37
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 cmnlib_a -> /dev/block/sde15
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 cmnlib_b -> /dev/block/sde36
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 control -> /dev/block/sda13
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 cota -> /dev/block/sda17
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 ddr -> /dev/block/sdd3
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 devcfg_a -> /dev/block/sde17
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 devcfg_b -> /dev/block/sde38
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 devinfo -> /dev/block/sde44
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 devlog -> /dev/block/sda10
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 dip -> /dev/block/sde45
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 dpo -> /dev/block/sde48
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 dsp_a -> /dev/block/sde10
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 dsp_b -> /dev/block/sde31
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 dtbo_a -> /dev/block/sde21
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 dtbo_b -> /dev/block/sde42
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 extra -> /dev/block/sda12
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 fataldevlog -> /dev/block/sda11
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 frp -> /dev/block/sda14
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 fsc -> /dev/block/sdf4
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 fsg -> /dev/block/sdf3
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 hosd_a -> /dev/block/sde14
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 hosd_b -> /dev/block/sde35
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 hvbmeta -> /dev/block/sda4
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 hyp_a -> /dev/block/sde3
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 hyp_b -> /dev/block/sde24
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 keymaster_a -> /dev/block/sde11
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 keymaster_b -> /dev/block/sde32
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 limits -> /dev/block/sde50
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 local -> /dev/block/sda15
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 lockbooter_a -> /dev/block/sde12
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 lockbooter_b -> /dev/block/sde33
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 logdump -> /dev/block/sde54
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 logfs -> /dev/block/sde52
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 mdtp_a -> /dev/block/sde8
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 mdtp_b -> /dev/block/sde29
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 mdtpsecapp_a -> /dev/block/sde7
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 mdtpsecapp_b -> /dev/block/sde28
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 mfg -> /dev/block/sdf2
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 misc -> /dev/block/sda6
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 modemst1 -> /dev/block/sdf5
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 modemst2 -> /dev/block/sdf6
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 msadp -> /dev/block/sde47
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 oem_misc -> /dev/block/sda7
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 padding0 -> /dev/block/sda1
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 padding3 -> /dev/block/sdd1
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 persist -> /dev/block/sda3
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 pg1fs -> /dev/block/sda5
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 pmic_a -> /dev/block/sde4
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 pmic_b -> /dev/block/sde25
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 qupfw_a -> /dev/block/sde18
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 qupfw_b -> /dev/block/sde39
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 radio_a -> /dev/block/sde5
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 radio_b -> /dev/block/sde26
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 ramdump -> /dev/block/sda8
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 reserve0 -> /dev/block/sda21
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 reserve4 -> /dev/block/sde57
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 reserve5 -> /dev/block/sdf7
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 sec -> /dev/block/sde43
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 sp1 -> /dev/block/sde49
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 ssd -> /dev/block/sda2
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 sti -> /dev/block/sde53
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 storsec -> /dev/block/sde55
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 system_a -> /dev/block/sda18
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 system_b -> /dev/block/sda19
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 tool_diag -> /dev/block/sda9
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 toolsfv -> /dev/block/sde51
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 tz_a -> /dev/block/sde2
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 tz_b -> /dev/block/sde23
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 userdata -> /dev/block/sda20
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 vbmeta_a -> /dev/block/sde20
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 vbmeta_b -> /dev/block/sde41
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 vendor_a -> /dev/block/sde19
lrwxrwxrwx 1 root root 16 1970-01-30 10:42 vendor_b -> /dev/block/sde40
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 xbl_a -> /dev/block/sdb1
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 xbl_b -> /dev/block/sdc1
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 xbl_config_a -> /dev/block/sdb2
lrwxrwxrwx 1 root root 15 1970-01-30 10:42 xbl_config_b -> /dev/block/sdc2