I'm aware of this and I have tried it. When I select QIO it can't load the partition table:
rst:0x3 (SW_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 188777542, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:2
load:0x3fff0030,len:7368
load:0x40078000,len:14956
ho 0 tail 12 room 4
load:0x40080400,len:4404
entry 0x40080694
I (29) boot: ESP-IDF v4.3-rc-2-g88c2b69c6-dirty 2nd stage bootloader
I (29) boot: compile time 08:23:05
I (29) boot: chip revision: 3
I (34) boot_comm: chip revision: 3, min. bootloader chip revision: 0
I (41) qio_mode: Enabling default flash chip QIO
I (46) boot.esp32: SPI Speed : 40MHz
I (51) boot.esp32: SPI Mode : QIO
I (55) boot.esp32: SPI Flash Size : 4MB
I (60) boot: Enabling RNG early entropy source...
E (65) flash_parts: partition 0 invalid magic number 0x44ce
E (72) boot: Failed to verify partition table
E (77) boot: load partition table error!
Considering it runs code from the embedded flash, it really needs to operate as fast as possible.
I am using the ESP-IDF 4.3 release branch if that makes a difference. I purchased this dev board from Digikey:
https://www.digikey.com/en/products/det ... 1/13532113