According to https://www.raspberrypi.org/products/raspberry-pi-4-model-b/specifications/ RPi4 uses Broadcom BCM2711 but when you look at /proc/cpuinfo you get a BCM2835 ?
$ grep Hardware /proc/cpuinfo
Hardware : BCM2835
It seems normal because even on an old raspbian Rpi3 I get the same answer when I should get BCM2837 so how to get “directly” the correct answer ? (without computation if it is possible)