I have been attempting to mount a SDXC (exFAT) card into the built-in MMC reader in my laptop. I keep getting "mmc0: error -110 whilst initialising SD card" errors in dmesg and the device is never registered in lsblk or elsewhere (e.g. /dev). I can't reformat the drive because the system can't see the device. I've installed the exfat-utils and nothing changed. My MMC can read SDHC cards just fine. Also, the SDXC card is new and my DSLR camera can use it just fine, so the card isn't defective.

I suspect that perhaps my MMC is just incapable of reading SDXC cards, but I can't find out any information on it (e.g. maker, model, etc). How do I get that information?

I am running Fedora 26 on a System 76 Gazelle laptop (which are designed to have linux compatible hardware). The laptop is about 2 years old.

1 Answer 1


I had the same problem. I think the problem is that your card reader doesn't actually support sdxc.

This is what happened to me:

1) First I installed the right drivers to read the exFAT filesystem

sudo apt-get install exfat-fuse exfat-utils

that didn't solve the problem, but it was a first step.

2) I bought a card reader that can actually read sdxc cards.

I thought that any sd card reader would do, or that any sdhc card reader would do. But no.

It was harder than I thought to find a card reader that actually clearly declares to be able to read microSDXC. Some say that they read SD, SDHC, SDXC and microSD. I didn't trust those.

In the end I bought a Kingston FCR-HS4, plugged it into a USB 3.0 port, and everything works at amazing speeds.

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