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#1 2013-04-24 05:29:22

tel
Member
Registered: 2013-04-24
Posts: 3

New EFI question

Just got a new Lenovo T430 with 180 GB SSD and Windows 8 installed.

This isn't going to be a true "dual boot" system.

My goal is to install Arch on a new, fully encrypted partition on the SSD, with the /boot partition on an external USB drive.  If the USB drive is inserted, then it will preferentially boot Arch.  On the other hand, if the USB isn't inserted when the system starts, it should just start Windows 8.

Will I need an EFI partition on the USB drive in addition to the EFI partition for Windows 8 that's already on the hard drive?

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#2 2013-04-24 16:11:28

srs5694
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From: Woonsocket, RI
Registered: 2012-11-06
Posts: 719
Website

Re: New EFI question

That's one way to do it. You'd configure the firmware to boot from the USB drive preferentially, so that when it's inserted, the firmware will go to the ESP on the USB drive, and when the USB drive is unplugged, the firmware will boot Windows (or whatever).

Another way to do it would be to install rEFInd on the computer's ESP and give it a default setting that would cause it to boot the Linux kernel in the USB drive's /boot partition. Then, when you insert the ESP, rEFInd would come up and it would boot the Linux kernel by default; and when the USB drive is detached, rEFInd would come up and boot something else (if only Windows is installed, it would be the only available option). I don't think this would work with gummiboot or GRUB, though, since they don't dynamically adjust their boot options with every boot.

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#3 2013-04-24 16:39:38

tel
Member
Registered: 2013-04-24
Posts: 3

Re: New EFI question

Thank you very much!  That answered my question.

As someone new to UEFI, my next question is: if I do the first suggestion (that is, have the computer preferentially boot the USB, if it's available), do I need a separate boot partition on the USB stick in addition to the EFI partition, or is a single EFI partition adequate?

Does the kernel go in /boot or in /boot/EFI.  If the latter, then an EFI partition alone on the USB drive would be adequate.  Do I have this right?

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#4 2013-04-24 16:47:54

teateawhy
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From: GER
Registered: 2012-03-05
Posts: 1,060
Website

Re: New EFI question

A single EFI partition is adequate. Pacman copies new kernels to /boot/... , that means if you mount your EFI partition to /boot new kernels are copied to the EFI partition.
The filename does not change by kernel version, so there is no need to change configuration.
EDIT: Only update the system with the usb stick plugged in , or you will receive some errors...

Last edited by teateawhy (2013-04-24 16:49:43)

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#5 2013-04-24 17:44:05

tel
Member
Registered: 2013-04-24
Posts: 3

Re: New EFI question

Thank you!  So if I understand you correctly, the USB stick has one EFI partition, and that partition can be mounted as /boot.  Does that sound right?

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#6 2013-04-24 21:57:18

srs5694
Member
From: Woonsocket, RI
Registered: 2012-11-06
Posts: 719
Website

Re: New EFI question

tel wrote:

Thank you!  So if I understand you correctly, the USB stick has one EFI partition, and that partition can be mounted as /boot.  Does that sound right?

Yes.

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