How is the maximum amount of microSD in fact?

Question

Mobile devices

Hello, I have such a question, I set myself the task of buying a 400 gig microSD card and a smartphone as a player, or a player.
But for some reason, some manufacturers indicate a maximum volume of 128 gigabytes or 256, although if this volume is only SDXC, then they are up to 2TB.
Some smartphones also have a maximum of 400, and some have 512, and someone with a reserve for the future has 2tb (the maximum for this type).
So it became curious, or the manufacturer writes the volume according to the maximum existing at the moment, and if the smartphone is last year, and there were not 400 gigabyte flash drives, then they wrote, for example, 256 or 128 ....
UPD: thanks to everyone, I realized for myself that the manufacturer indicates what they tested with or what was sold at the time of release, and because. memory cards with volumes of 128, 256 and 400 gigabytes are a little new, then devices released a year and a half ago, and announced two years ago, come with an indication of 256 gigabytes, for example, and older ones generally 128, but if 128 holds, then this is SDXC and already up to 2tb in theory...

Answer 1

I rummaged through the Internet about controllers serving sdxc and did not find any mention of any limits, but of course it's better to ask the hardware guys.
But theoretically, an artificial limit is possible, defined in the software part of the device, which actually processes the logic and supports exfat ... why the manufacturer might need it - it's very simple, to distinguish between categories of devices by low end / mid end / high end segments, because in practice they it is already very difficult to do it than others. For example, a device that is not very productive but with good and capacious storage is suitable for people, the manufacturer does not like that people in this category buy a cheap and not expensive device, set a limit on the size and voila - people are forced to buy an expensive device.
If this is a linux device, such a limit, if it exists, with some degree of probability can be removed by flashing the device, but there should be so many conditions that Chinese / Korean manufacturers have not fulfilled for a long time (GPL license and issuance of source codes).

Answer 2

"Fact" is a matter of change as technology develops. A few years ago, a relative of mine went on a tour to Thailand. In a souvenir shop, I succumbed to the persuasion of the seller and bought a 256 GB photo flash drive (microSD). He had some doubts, but the salesman convinced him, citing a "compelling argument" that Thailand is a country of high technologies, and everything that is most advanced first appears here. I brought it home, and froze showed the real capacity - 4 gigabytes. A guy got pierced, it's an everyday thing ...
But now on Ali I see an offer of 256-gigabyte photo flash drives, and I think, with a real capacity, because from Samsung. Of course, I can’t afford to spend 4,000 rubles to check the real capacity, but Samsung is an office with a name that has not been seen in the scam before.
So your question can only be accurately answered in relation to a specific time.