[UPDATED]I'm triyng to dual boot Kali for experimenting and Debian for daily use on a brand new 250 GB Samsung SSD 850 pro. I also have a Windows 10 OS for gaming but it's on anohter SSD (identical to the other: Samsung 850 pro 250 GB). I'm using advanced graphical install but I have a major problem: after installing one of the two above, the other won't start at all giving me a wall of "Buffer I/O error - logical block 0 - async page read".[EDIT]-Last statement isn't true: system starts after many minutes and after the errors.- I install Kali, debian becomes unusable. I reistall Debian, Kali becomes unusable. And so on. Windows 10 is always seen by Grub, I never touched it and still work ok so far. SSD is partioned in 4 spaces: 200 MB boot, 5.9 GB Swap, 125 GB etx4 for Debian, 125 GB ext4 for Kali.

I know I'm doing something wrong but I dunno what.

Someone can help?

Were it me, I would run Debian with Windows 10 dual boot. I would only run KALI as a live-cd or virtual machine under Debian or Windows. KALI has ALWAYS caused boot issues in multiboot configurations for me. Even when I can solve them, I do not trust it and will not recommend it.

Maybe you are right. But then, why I'm experiencing the same issue on Kali when reinstalling Debian? I mean, if it's a problem with Kali and dual booting, when I reistall Debian with its Grub all should work ok, am I wrong?

When you install the first Linux, use the manual install, install the bootloader to the MBR. The second linux don't install the bootloader. Then, boot into the first Linux and reinstall the bootloader. That should give you both distros on the same drive.

A significant piece of information which you have not stated is whether you are using UEFI for all of the installs. A default pre-installed windows would be UEFI so you need both Debian and Kali UEFI. Personally, if you are planning to use Kali to learn computer forensics, using it from the usb is probably the best way tostart. You can even add persistence as explained at their site below.

https://docs.kali.org/downloading/ka...sb-persistence

If you are using EFI, on which drive is the EFI partition and what does it contain? Run parted -l as root from either Debian or Kali and post the output here or mount the EFI partition and take a look. You haven't posted enough information for anyone to give you any specific help so posting at least this info would be a start.

Actually what I wrote on the main post isn't true. After installing Debian (or Kali), Kali (or Debian) starts.
Starts after all those errors below and some minutes:

https://s8.postimg.org/r3owq4k6d/20171217_191605_1.jpg
https://s8.postimg.org/6jk2rpwqd/20171217_191623_1.jpg

And after the countdown on this screen:

https://s8.postimg.org/qe64dw1o5/20171217_191702_1.jpg

This is what the partioner sees while reinstalling Debian:

https://s8.postimg.org/8o4fsviyd/20171217_210811_1.jpg

This is what grub sees:

https://s8.postimg.org/5h9w8xlk5/20171217_191413_2.jpg
https://s8.postimg.org/mhsshmtgl/20171217_191512_1.jpg
https://s8.postimg.org/wt55ahvid/20171217_191514_1.jpg

As suggested by AwesomeMachine I'm now entering Kali for reinstalling Grub.

Thanks for the photos. Try blowing some air into the CD/DVD drive, and wipe off the optical disk itself. /dev/sr0 is the CD/DVD drive. On boot it tries to read it, but it's having trouble. Otherwise, take the optical disk out of the drive.

I want to kill myself. Right now.

Thank you, my savior... Errors are gone.
Anyway why cheching for drives and USB sticks (I realized this later) after i choose kali/Debian to start?

Still, I have a problem. The countdown remains:

https://s19.postimg.org/xc4kv9awj/20171217_234720_1.jpg

OS won't start until the contdown finishes...
EDIT: reading in other places, seems like SWAP is deactivated or have other issues. Must check.

No, we don't kill ourselves here Are you trying to use the same swap partition for both OSs?

Yes. As you can see from the partitioner pic above, I only have a single SWAP partition.

Find which disk is referred to by the uuid in your countdown wait time and edit that entry in fstab

Do you really need swap? Any box above 3GiB does not need SWAP in my point of view.
Swap was needed on a pentium 120 with 128MB of ram in my experience.

When I used swap, I used it for any linux os on the box. When you do not use tuxonice, it does not really matter. look out for the reinitialise swap with random key feature. so swap gets overwritten during initialisation.

Did you apply root_delay in your grub? it seems you are using usb drives. some external drives need quite some time to get ready. test it with 30 seconds rootdelay and check if the errors are gone

It really depends upon your usage and priority. If system stability under load has no value to you, you can work without swap. If you need production uptime, even under unexpected or massive load, then swap is needed.