Author Topic: Plop not detecting OS on external SSD or Flash Drive (formatted as MBR)  (Read 664 times)

comphacker

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As the title says, I've tried to use Plop to boot both Windows 10 (BIOS, not UEFI), and Ubuntu (same), and no matter what I try, Plop won't detect it nor boot from it. It only detects the built-in ssd of my laptop. Using Plopkexec, however, I am able to load Ubuntu manually (it's also not automatically detected, so I need to manually run kexec). I can give more information, but as I don't know what is and isn't helpful, so let me know.

~comphacker

Golffies

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Re: Plop not detecting OS on external SSD or Flash Drive (formatted as MBR)
« Reply #1 on: February 20, 2019, 12:56:59 PM »
Hello,

I am no sure to be the one fixing your problem, but a least helping to make the case more obvious.
Firstly, are you talking about Plop Linux booted from its live-CD, or do you make use of a permanent install of the Plop boot manager on your system ?

Secondly, do we agree that you chose "booting from USB" from the menu, when trying to launch your operating systems from your external HDD ?

Regards.

comphacker

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Re: Plop not detecting OS on external SSD or Flash Drive (formatted as MBR)
« Reply #2 on: February 20, 2019, 22:54:01 PM »
I'm actually using Plop over PXE boot, served off a Raspberry Pi. I've tried booting from the external drive using the "boot from USB" menu option, as well as by trying to boot any of the hdb partitions. Booting HDA partitions only boots the main drive in the laptop.

Golffies

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Re: Plop not detecting OS on external SSD or Flash Drive (formatted as MBR)
« Reply #3 on: February 21, 2019, 14:20:27 PM »
Well, you did as I would have done.

Just remembering from the documentation that Plop needs BOOTMGR for booting Windows or GRUB in case of Linux, may you confirm that both Windows and Linux have their loaders installed on respective partitions  ? I guess yes, just brainstorming.

comphacker

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Re: Plop not detecting OS on external SSD or Flash Drive (formatted as MBR)
« Reply #4 on: February 23, 2019, 06:56:44 AM »
I'mt not sure I can use regular Plop (just Plopkexec), since my laptop apparently has a built-in USB hub. Do you know if it's possible to boot Windows's BOOTMGR from plopkexec? Though I don't seen to need GRUB in the case of Linux, simply because I'm using Plopkexec.

Golffies

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We may have at least one first answer. From the doc:

PlopKexec is based on a Linux Kernel and can load only other Linux kernels!


It explains why you cannot boot Windows from the PlopKexec boot manager.

Coming back to your assumption that your motherboard makes use of an embedded USB hub, which prevents you from successfully booting with the Plop (regular) boot manager, it might worth to be double checked. Your USB controler(s) may present more than one bus. But we may be wrong at concluding this is an embedded "hub". According to my limited practical knowledge, each "bus" is hard linked to selected USB ports (the type A female sockets which we plug our devices to), and the device number is non relevant, assigned on the fly, each time we plug-unplug-replug a device, whatever the USB port/socket chosen. For instance, two USB ports on the right rear may be linked to bus #3 and two others on the left rear may be linked to bus #2. It is the way they are soldered on the motherboard which commands to which bus they belong. However, I am not sure there is an "internal hub" here.

You may give a try to the Plop boot manager once more.

Golffies

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Hello !

I went a little deeper into the issue of USB ports and hubs. I would have liked to have given a more precise answer in the case you were describing.

Each USB controller has a roothub, to which several physical ports can be connected by the same bus; all ports connected to the same controller will then have to share the bandwidth of the same bus.

Motherboard designers adopt a more efficient design, and choose to connect the USB ports to different controllers, when they are available on the chipset, in order to provide dedicated bandwidth for each port, or for each group of two ports for example.


All this to confirm that the "hubs" you see on your machine are quite normal, these are the roothubs through which the ports are connected to the controllers, and they are found on all machines. They should not prevent the Plop's boot manager from working.