burtyb
Posts: 35
Joined: Sat Mar 05, 2016 4:19 pm

Accessing SD/eMMC after booting Linux as a USB device

Thu May 30, 2019 7:08 pm

Using the CMIO board (with J4 set to EN) I'm booting Linux over USB with rpiboot.

After it's booted how can I access the SD/eMMC for local storage/swap/etc. (without changing J4 to DIS)?

The kernel seems to "sort of" be able to see it during boot

Code: Select all

[    1.763745] sdhost: log_buf @ bad01000 (fad01000)
[    1.851656] mmc0: sdhost-bcm2835 loaded - DMA enabled (>1)
[    1.860553] of_cfs_init
[    1.865470] of_cfs_init: OK
[    3.452455] mmc0: error -110 whilst initialising MMC card
[    4.928296] mmc0: new high speed MMC card at address 0001
[    4.936418] mmcblk0: mmc0:0001 BJTD4R 29.1 GiB
[    4.943323] mmcblk0boot0: mmc0:0001 BJTD4R partition 1 4.00 MiB
[    4.951747] mmcblk0boot1: mmc0:0001 BJTD4R partition 2 4.00 MiB
[    4.960017] mmcblk0rpmb: mmc0:0001 BJTD4R partition 3 4.00 MiB
[    4.968834] mmcblk0: error -110 sending status command, retrying
[    4.977113] mmcblk0: error -110 sending status command, retrying
[    4.985264] mmcblk0: error -110 sending status command, aborting
[    4.993596]  mmcblk0: unable to read partition table
[    5.002287] mmc0: card 0001 removed
[    5.358260] mmc0: new high speed MMC card at address 0001
[    5.366211] mmcblk0: mmc0:0001 BJTD4R 29.1 GiB
[    5.372904] mmcblk0boot0: mmc0:0001 BJTD4R partition 1 4.00 MiB
[    5.381034] mmcblk0boot1: mmc0:0001 BJTD4R partition 2 4.00 MiB
[    5.389033] mmcblk0rpmb: mmc0:0001 BJTD4R partition 3 4.00 MiB
[    5.397391] mmcblk0: error -110 sending status command, retrying
[    5.405374] mmcblk0: error -110 sending status command, retrying
But trying to access it gives an error.

Code: Select all

# dd if=/dev/mmcblk0 of=/dev/null bs=4M status=progress
dd: error reading '/dev/mmcblk0': Input/output error
If after booting I switch J4 to DIS I can access the eMMC/SD without issue but I'd like a way of doing it in software without needing to change the jumper.

I'm guessing it must be possible hardware wise as you can turn it into a MSD using rpiboot without changing J4 from the EN position.

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