Well I think the answer is a bit longer. Its about understanding the changes along the line since the old days, and their interdependencies.
A legacy PC in the old days had a bios to start from, and typically the drives were partitioned with the MBR/MSDOS partitioning scheme, max. 4 Partitions or 3 plus an extended one for some logical drives. Something we nowadays call legacy install.
Around 2010 the industry decided to introduce the new efi bios as mandatory for new designs. I think it came along with Windows8. New features: the GPT partitioning scheme (up to 128 partitions) and Secure Boot (SB). Some very early efi systems did not have SB on board, that came with a slight delay. efi meant a new way to boot the computer. You will need an ESP with FAT32 filesystem for the boot files. To support legacy installs and boot the CSM mode could be enabled. BTW: Some of the older efi implementations are really crappy.
Around 2020 new designs have skipped the CSM from the bios, these machines can only boot in efi mode. My travelling laptop is such a machine. This is a very short and rough summary of the history.
Now we come to Windows, parallel installs are another complication: you mentioned XP. XP can only be installed on MBR drives and legacy/CSM bios, it does not understand GPT and efi at all. Win7 SP1 can do both, legacy install on MBR drives, or efi install on GPT drives. Same for 8/9/10. What win11 is concerned, I don't know. My last Win is Win7. As far as I know Win7 efi mode can't deal with SB. In any case Windows is very strict: MBR drive installation always is legacy install, GPT drive installation always is efi mode. And just changing the options in the bios/efi won't do any good, you are stuck if you think you can simply change between legacy and efi mode. Ok, there are ways to change, but its a lot of hasle ...
Another Windows topic is fast boot which is basically hibernation. If that is enabled, you can't dual boot with any other operating system. You have to switch it off.
Dual booting: to make you live easy the best approach is to install Windows first, if possible on a separate drive, and the Linux using the same mode Windows was installed on. That will easily work.
Note: there are modern PCs/laptops that resist easy dual booting a Linux parallel to Win10/11.
Linux systems are much more flexible. They can do legacy install on MBR drives, but also on GPT drives, with the small details that in such a case you need a bios_grub partition for holding parts of grub. I have done both. Naturally also efi installations on GPT drives. What I never tried is an efi installation on a MBR drive.
Note: to make use of drives larger than 2 TB these need to be GPT partitioned.
Last but not least, on efi installations you have to make sure that you boot your installation media in the right mode. On my efi main boards that support CSM I get these tools twice: e.g. when I use a SanDisk stick, there is one entry in the boot menu/override that is simply called SanDisk. That starts the installer in legacy mode. Then there is a second entry with the prefix UEFI: SanDisk, that starts the installer in efi mode. The start mode determines the grub installation mode, at least on Debian versions. Unfortunately, Debian installers do not tell you on the boot screen in which mode they are started. To overcome this deficiency you may use Ventoy as a tool. Ventoy tells you the booted mode.
Personally, I switch off SB and delete all keys in the bios on all of my systems to avoid the additional hasle I have with it.
As you see the technical details are many and if you are not up to the latest information may be very confusing. You need to really understand what kind of machine you are driving, and what you want to achieve with it.
Summary: you need to understand these dependencies and complications, its no more that easy as it was 20 years ago. But its still possible to install a modern Linux in legacy mode with no SB on a MBR or GPT disk. You just need to make the right steps.
I am sure I have forgotten one or the other relevant topic.
A legacy PC in the old days had a bios to start from, and typically the drives were partitioned with the MBR/MSDOS partitioning scheme, max. 4 Partitions or 3 plus an extended one for some logical drives. Something we nowadays call legacy install.
Around 2010 the industry decided to introduce the new efi bios as mandatory for new designs. I think it came along with Windows8. New features: the GPT partitioning scheme (up to 128 partitions) and Secure Boot (SB). Some very early efi systems did not have SB on board, that came with a slight delay. efi meant a new way to boot the computer. You will need an ESP with FAT32 filesystem for the boot files. To support legacy installs and boot the CSM mode could be enabled. BTW: Some of the older efi implementations are really crappy.
Around 2020 new designs have skipped the CSM from the bios, these machines can only boot in efi mode. My travelling laptop is such a machine. This is a very short and rough summary of the history.
Now we come to Windows, parallel installs are another complication: you mentioned XP. XP can only be installed on MBR drives and legacy/CSM bios, it does not understand GPT and efi at all. Win7 SP1 can do both, legacy install on MBR drives, or efi install on GPT drives. Same for 8/9/10. What win11 is concerned, I don't know. My last Win is Win7. As far as I know Win7 efi mode can't deal with SB. In any case Windows is very strict: MBR drive installation always is legacy install, GPT drive installation always is efi mode. And just changing the options in the bios/efi won't do any good, you are stuck if you think you can simply change between legacy and efi mode. Ok, there are ways to change, but its a lot of hasle ...
Another Windows topic is fast boot which is basically hibernation. If that is enabled, you can't dual boot with any other operating system. You have to switch it off.
Dual booting: to make you live easy the best approach is to install Windows first, if possible on a separate drive, and the Linux using the same mode Windows was installed on. That will easily work.
Note: there are modern PCs/laptops that resist easy dual booting a Linux parallel to Win10/11.
Linux systems are much more flexible. They can do legacy install on MBR drives, but also on GPT drives, with the small details that in such a case you need a bios_grub partition for holding parts of grub. I have done both. Naturally also efi installations on GPT drives. What I never tried is an efi installation on a MBR drive.
Note: to make use of drives larger than 2 TB these need to be GPT partitioned.
Last but not least, on efi installations you have to make sure that you boot your installation media in the right mode. On my efi main boards that support CSM I get these tools twice: e.g. when I use a SanDisk stick, there is one entry in the boot menu/override that is simply called SanDisk. That starts the installer in legacy mode. Then there is a second entry with the prefix UEFI: SanDisk, that starts the installer in efi mode. The start mode determines the grub installation mode, at least on Debian versions. Unfortunately, Debian installers do not tell you on the boot screen in which mode they are started. To overcome this deficiency you may use Ventoy as a tool. Ventoy tells you the booted mode.
Personally, I switch off SB and delete all keys in the bios on all of my systems to avoid the additional hasle I have with it.
As you see the technical details are many and if you are not up to the latest information may be very confusing. You need to really understand what kind of machine you are driving, and what you want to achieve with it.
Summary: you need to understand these dependencies and complications, its no more that easy as it was 20 years ago. But its still possible to install a modern Linux in legacy mode with no SB on a MBR or GPT disk. You just need to make the right steps.
I am sure I have forgotten one or the other relevant topic.
Statistics: Posted by rolf3945 — 2025-01-18 22:40