Pi SDRAM Drive - How does the image work?

[Tango]

I'm using a Pi 3B and I bought a 256GB SD card for it (since it wasn't much more than smaller cards). I set up the image and made sure it booted. Then I started doing the things I wanted to do, including enabling ssh. First, I used the config utility to expand the partition to fill the whole size of the SD card. (And then, of course, rebooted.) I put the SD card in a reader for my Mac and it mounted with the name of "boot." I checked info on the volume and it reads as around 250MB. There are no other partitions or anything on the drive that Apple's Disk Utilities can find.

Then when I booted my Pi with RetroPie on it, again, and ssh'ed in to work on it, and did this:

Is /dev/mmcblk0p1 the boot partition?

Just what exactly happens during the boot process where I go from a ram disk that, according to Disk Utilities, is under 25 MB, to a partition close to the full size of the available RAM on the SD card? And why is it that I can't find any trace of that extra RAM on the card being used on the device itself when I check it out on my Mac?

[mitu]

@Tango said in Pi SDRAM Drive - How does the image work?:

Is /dev/mmcblk0p1 the boot partition?

Yes.

The sdcard is formatted with 2 partitions:

• one is the boot partition, which is FAT32 and can be read from other (non-Linux) systems
• seconds one is a Linux Ext4 partition, which cannot be read natively by macOS or Windows systems. It's not a SDRAM drive.

[Tango]

@mitu : Thanks, makes perfect sense. I suspected it was something like that.