mmcblk number changed on kernel update

[craigmcqueenir]

I have an imx8mm based system. I'm using Yocto dunfell with meta-freescale providing kernel 5.4.107.

Recently I tried to update the kernel to 5.4.119. I found it didn't boot, because the mmcblk number changed from 2 to 0. So my root partition is no longer mmcblk2p3, but mmcblk0p3.

The eMMC was numbered mmcblk2 so far because it's on usdhc3.

Having these device numbers changing (on a minor kernel update surprisingly) is unexpected and prevents the board from booting. Is there something I can put in the device tree to preserve the numbering of mmcblk2? Any other solution?

[igorpadykov]

Hi Craig

for mmcblk numbering one can look at Table 54. Linux uSDHC relationships

i.MX Linux User’s Guide​

Best regards
igor

[craigmcqueenir]

Thanks for replying. However, your reply doesn't tell me anything more than what I had already said:

The eMMC was numbered mmcblk2 so far because it's on usdhc3.

My question is, why does this no longer hold true after a Linux kernel upgrade from 5.4.107 to 5.4.119? And how can this be fixed?

[igorpadykov]

>why does this no longer hold true after a Linux kernel upgrade from 5.4.107 to 5.4.119? And how can this be fixed?

since this is general linux question recommended to post it on kernel mail list

http://vger.kernel.org/vger-lists.html

Best regards
igor