Hi, finally (after a few days) I made it. thanks for the feedback, and trying to help.
My english is little bad but we can go through it, I guess..
Just a note, Slackware 14.2 didn't boot up, I just got a black screen, I didn't spend time on it because I wanted Slackware current which had elogind and droplineGnome
Ok first, a little of background knowledge.
I'm using something like an ezbook x3 pro I don't know (in Brazil they sale it with a different brand) but I think its the same.
This notebook has a eMMC "hd" in the main board which makes Linux see this as /dev/mmcblk0 (not /dev/sd*) ok, that's not a problem.
It has a microSD reader, and my notebook came with a 32GB microsd card, and I wanted to install Slackware on it, because in the eMMC already had Windows10
The problem is, this microSD reader is not part of mainboard, but a hub connected to it, a realtek hub, and Slackware didn't see it.
and I mainly created this thread because Slackware Current Setup didn't see this microSD reader, and the modules needed was not available in setup.
I am a long date Slackware (patreon) user and I really want to see it out of the box with those things, but ok, its Slackware, isn't?
So I installed Slackware in the microSD card with a usb card reader, and it worked because the setup saw this as /dev/sdb (/dev/sda was the usb Slackware installer stick).
But when I put the microsd on the notebook card reader it didn't boot up because huge.s kernel didn't see the microsd in the notebook (without the external card reader).
So here the steps:
First you need Grub...actually I don't know if you can achieve with elilo, but lets do with grub.
But before it, you need an EFI partition in the eMMC "hd", this partition need to have enough space to hold the kernel and the initrd
(Windows 10 creates this partition with 100MB which is not enough, 200MB you can go well...).
Ok with an EFI partition set up, you need to install Grub in the eMMC
(you can do all this with a live distribution or a chroot Slackware in the external usb microsd reader)
grub-install /dev/mmcblk0
This command will create an entry in the UEFI menu, and a folder in your EFI partition (Slackware will create a Slackware folder, Ubuntu will create an ubuntu folder, it depends on the distribution)
in this folder you will put the grub.cfg because the system will be in the mmcblk1 (the microsd) but Grub didn't see it too. (I didn't have time to fix that)
the grub.cfg generated by ubuntu, tells grub to get grub.cfg from the mmcblk1 but grub didn't see this "hd" so you need to put your grub.cfg (with all the entries) inside this folder, or you got a black screen with a grub command line but you still can load a grub.cfg with the configfile command.
(Actually grub is very simple and fun to work with)
in the same folder you will put the Slackware kernel (huge.s) and configure grub to get the kernel from this folder. You can do it with UUID, /dev/(***) or (hd0,gpt1) (if your EFI is the first partition), you just need to tell where is your EFI partition and the folder where the kernel is.
now you have to create the initrd for Slackware, if you in a live distribution you will need to chroot in your Slackware installation
don't forget to bind the necessary system files before chroot (I bind dev proc and sys, don't now which one is really important)
You will create the initrd with this command
mkinitrd -c -k 5.4.63 -f ext4 -r /dev/mmcblk1p2 -m \
usb-storage:ehci-hcd:ehci-pci:xhci-pci
hci-pci:xhci-hcd:uhci-hcd:\
rtsx_usb_ms:usbnet:memstick:mac_hid:r8152:mii:hid_multitouch:mac_hid:usbhid:rtsx_usb_sdmmc:rtsx_usb: hid_generic:mmc_block:ahci:sdhci_pci:cqhci:i2c_i801:sdhci:i2c_hid:libahci:hid:jb2:mbcache:\
ext4 -u -o /boot/initrd.gz
Just copy and paste in your console or create a shell script.
The order of the modules is very important (I didn't know that), so don't change that, the important module is the rtsx one
This will create an initrd which will load the realtek card reader in the right order.
(That was a fight because with the wrong order, sometimes Slackware boot didn't see the microsd, sometimes it loads the microsd as mmcblk0 and the eMMC as mmcblk1
sometimes it unload the eMMC so mmcblk0 didn't exist anymore...I studied which modules Ubuntu loaded and in which order, and I make the initrd, and it worked!)
Now the microSD is set in /dev/mmcblk1 (your Slackware partition will be something like /dev/mmcblk1p1)
After that, you just copy the initrd.gz generated to your Slackware folder in the EFI partition
Configure grub.cfg to load the initrd.gz
Put rootwait in the kernel parameter.
Done.
It was a pleasant linux travel, I learn a lot (in this four days) about Grub, UEFI, efibootmgr, mkinitrd, and kernel modules.
Thanks you all and hope it will help someone.
(Brazil).
Here is my relevant Grub configuration
linux (hd0,gpt1)/efi/Slackware/vmlinuz root=UUID=a5d1f242-b47f-4b59-851b-6e0f32da9d46 ro rootwait rootdealy=5
initrd (hd0,gpt1)/efi/Slackware/initrd.gz
Here is my relevant Slackware fstab
/dev/mmcblk1p2 / ext4 defaults 1 1
Just a footnote if you install grub from another distribution instead Slackware sometimes grubx64.efi had the grub.cfg location hardcoded in the binary
For example: Ubuntu creates a folder ubuntu in the EFI partition, and its grubx64.efi will always look on this folder no matter which folder you choose.
Just a note in case you got a grub black screen...
