Sorry about my English Writing
I just installed ubuntu 17.10. Now whenever I open my BIOS settings ubuntu is my first option in the efi boot options list and I can not boot my USB. I can boot from DVD in legacy ....
Please help me :(
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Most computers provide a built-in boot manager that enables you to select which option to boot when you power on the computer; however, most computers do not launch this boot manager automatically -- you must press a key at a particular point to open it. Unfortunately, what key you must press varies from one computer to another. It's usually a high-numbered function key (F8 or above), Esc, or Enter; but it could be anything. (Many Lenovos use Enter, IIRC; but my IdeaPad U530 uses F12.) Some computers briefly display a prompt about keys to press to do various things -- the boot manager may be called that, or something more obscure, like "BBS popup menu." Some computers don't display such a message, or omit the boot manager from the list of keys shown as options, although something will actually work. Worse, some computers are unresponsive to keystrokes at this critical point unless you change firmware settings to disable a "fast start" option -- but some call this enabling a fuller USB initialization. Given all these options, you may need to poke around randomly, check your manual, ask on a Lenovo forum, or hope that somebody familiar with your specific model reads your query here and posts an answer.
As sudodus suggests in a comment, it could also be that your USB drive is not prepared properly. In particular, most tools for preparing USB drives from
.iso files need to explicitly copy a boot loader to the USB drive; but some tools omit the EFI-mode boot loader (or the BIOS-mode boot loader, but that's a rarer omission). There are also occasional machine-specific quirks -- a USB drive that boots fine on Machine A may not be recognized by Machine B, but another USB drive will boot fine on both computers, or might work on Machine B but not on Machine A. Thus, changing tools (or perhaps adjusting options in whatever tool you used) may help. See this page of mine for my comments on some common tools. (Quick version:
dd and Rufus do a better job than most. Pen Drive Linux, aka YUMI, was useless for creating EFI-bootable media the last time I checked.)
If you've verified that your USB drive is properly prepared and you're convinced that your firmware is particularly troublesome, you might try installing my rEFInd boot manager to your hard disk. This software will scan for bootable media and present a menu of everything it finds. In theory, it should pick up a bootable USB drive, with the caveat that your firmware must initialize the USB hardware. Also, if you want to boot USB media in BIOS/CSM/legacy mode, you must adjust the
scanfor line in the
refind.conf configuration file.
I have the same problem with the same lenovo z50-70 I used to try every release of ubuntu and come back to the LTS release again. but it seems that ubuntu 17.10 has a problem. in Lenovo website people face the same problem like us with the same distro version. our laptops now are like locked closet .. we can't boot using USB we can't change settings on BIOS there.
PS: USB boots in another laptop.