r/linux4noobs • u/Imran_Delta • 23d ago
shells and scripting UEFI GRUB Vs MBR Windows
Like, I have windows on my HDD. The thing is, this HDD is old and is MBR. I can run Linux off if via uefi, but the windows partition has to be booted via the bios boot menu, problem is. Ppl in my house dunno about that. So I decided to add windows MbR to grub.
Thing is. Idk how;
(Distro is Manjaro, both of them are on the same drive. sda2 is the windows MBR, sda3 is Linux uefi. Windows is on sda5, Linux is on sda8)
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u/MycologistNeither470 23d ago
Things NOT to do in a production system. Item # 23: mixing MBR and UEFI in the same system.
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u/DavidJohnMcCann 23d ago
Linux will run on an MBR system — you should have chosen than at installation — do not try to mix UEFI and Legacy BIOS! The Linux installation should spot Windows and automatically add it to Grub — see here.)
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u/michaelpaoli 23d ago
Well, there's one EFI partition, it's not OS specific (even if presently only Linux is using it).
If all the OSes present, and their booting will deal with EFI, could change the system to EFI ... but as for Microsoft Windows, I've zero idea what one might need do on the Microsoft side for it to successfully deal with that (and that's really quite off-topic for a Linux subreddit anyway, so maybe best ask that somewhere else).
As for the Linux side of things, probably most any non-ancient Linux, can well handle EFI or MBR boot. And if the drive is formatted MBR, no reason it can't be converted to GPT with EFI - at least presuming all the OSes on it can handle GPT and boot (directly or indirectly) via EFI.
In fact I've already converted a fair number of drives from MBR to GPT - not super trivial to do, but also not all that hard either ... certainly not exactly rocket science.
And yes, GRUB does also support having a legacy BIOS partition on GPT, and with that, GRUB can still boot Linux in legacy MBR mode.
Anyway, you can adjust and reconfigure your Linux to boot either MBR or EFI, Probably likewise for your Microsoft goop (though I don't know exactly how to do that, and this isn't the subreddit for that). Probably best to have 'em both the same, either MBR or EFI - and likely EFI, though converting to GPT and EFI may be rather non-trivial, but should be very highly doable (certainly is for Linux, and I'd guess likewise for Microsoft, at least if the Microsoft goop isn't too ancient).
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u/Imran_Delta 23d ago
For clarification. I have 1 hard drive as MSDOS. And both windows and Linux is on it. My question is, can uefi grub reboot to a bios boot option? Even if that boot is MBR? Since Windows cannot be installed as UEFI on MbR even if it's possible. My attempt is adding a boot entry for (MBR) Windows in (UEFI) grub. Although it doesn't look like that's possible- So my conclusion is pretty much, use F12-
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u/Imran_Delta 23d ago
Basically, I used to have a SSD with Linux and Windows both on it. The SSD died. Then I moved grub to my only hard drive. Then I installed windows. Now I'm looking to see if I can use grub to boot windows (which is on the same drive as MBR). Linux was UEFI alongside windows from the start on the SSD (Now dead).
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u/skyfishgoo 23d ago
everything is moving to EUFI and mixing these disks on your machine is begging for issues.
you have more than one disk, put linux on one SSD and windows on another... use the HDD for media storage and backups because it's slow.
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u/tomscharbach 23d ago
You are planning a maintenance nightmare.
You might set up a "Want to run Windows?" sheet with simple, step-by-step instructions about how to enter BIOS to run Windows.
Better yet, if Windows is the operating system primarily used by the others, you might consider putting Windows in as "default" in the boot sequence (so that nobody else needs to enter BIOS) and boot your Linux build from BIOS Boot Menu.
My best and good luck.