Unable to mount root fs on unknown-block(0,0)[solved]

[Adel Ahmed]

UI'm trying to install gentoo on my cherry trail laptop, the root filesystem is btrfs on /dev/mmcblk0p2(there are no hard drives.
kernel config:
https://dpaste.com/57R8HF3LF
when the kernel panic lists available partitions it lists sda*(usb flash drive) but not /dev/mmcblk*

how Can I get gentoo to recognize the mmc?

[NeddySeagoon]

Adel Ahmed,

/dev/mmcblk* devices can be very slow. The kernel detects them asynchronously.
You need either rootwait or rootdelay= on the kernel command line.
However, if you use an initrd, the initrd must do the waiting. rootwait or rootdelay= on the command line will delay the mounting of the initrd as root.

rootwait will wait forever.
rootdelay= delays the given number of seconds

Use rootdelay= until it works, then switch to rootwait to get the fastest boot.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

[Adel Ahmed]

I tried rootwait yesterday, and 8 hours later the rootfs could not be detected, I'm suspecting a muissing kenrel module so far

[pietinger]

Adel Ahmed,

we would need more information about your laptop. Please boot with our GentooLiveCD and provide us the output of:

* dmesg
* lsmod
* lspci -nnk

(please use wgetpaste for it)

and the information if you try to boot WITH or without an initramfs. If WITH how was it built?

Maybe you miss only these:

[Adel Ahmed]

the kernel options did not resolve the issue, thanks for the ACL tip though.
I do not use an initrd
dmesg:
https://dpaste.com/3CDXTGUPV
lsmod:
https://dpaste.com/DBK5JXYZH

the memory card is connect by the ACPI bus i believe.
lspci:
livecd ~ # lspci -nnk

[zen_desu]

[pietinger]

Adel Ahmed,

what I did:

Searching in "lsmod" for modules which COULD be related to MMC (so, no sound modules ). Then I checked if they are enabled in your .config. These are missing:

[pietinger]

Internal note:

[Adel Ahmed]

thanks alot for your effort pietinger, I've built those modules into te kernel but the rootfs is still not detected, the r8723bs is the wifi module so I have it built as a module now.
@zen desu, I've copied over the initrd from the installation medium, now the rootfs is detected which should save me from using the liveusb medium until I figure this out, the boot process is stuck however at device fsid <uuid of root> devid 1 transid 899 /dev/mmcblk-p2 scanned by (udev-worker) and I get dropped to a dracut shell, this is progress nevertheless and should helpme narrow it down further

[Adel Ahmed]

It was a wrong uuid issue, i can now boot with initrd, let me post my new dmesg

[Adel Ahmed]

new system(booted with initird) lsmod:

[pietinger]

Hmmm this is strange ... your MMC is in this syslog NOW recognized ... directly from the kernel ... BEFORE initramfs is started (exactly as we want it) (look at the timestamp):

[Adel Ahmed]

GAAH, I think that was it, I changed root=UUID to root=PARTUUID and it boots without and initrd now, I have gone through that link to understand and it explained things perfectly, thank you very much pietinger

[pietinger]