On 12/13/2015 05:00 PM, Frank Cox wrote:

On Sun, 13 Dec 2015 16:48:25 -0500 ken wrote:

...

So far I've created on this new laptop a big, empty partition; in the BIOS enabled legacy booting and disabled UEFI; also in BIOS under Legacy Boot Order set "USB diskette on key/USB hard disk" on second priority. I've tried to boot from a usb thumbdrive three times and it failed all three times. I'm not understanding what's wrong.

I install Centos on pretty much everything by setting the bios to use USB as the primary boot device, then booting the Centos Live Image from a flash drive, then hitting the "install to hard drive" icon on the Live Desktop. After the installation is complete, set the bios back to use the hard drive as the primary boot device and you're all set.

Aha! The problem was that, despite legacy was enabled and uefi was disabled, the bios followed 'uefi boot order' and disregarded 'legacy boot order'. Once I changed uefi boot order appropriately, the bios booted the thumbdrive.

However, when the centos menu came up, i.e.:

Install CentOS 7 Test this media & install CentOS 7 Troubleshooting -->

[use 'e' or 'c' keys]

regardless of which of the above three I selected via right-arrow, I was prompted by:

error: invalid magic number. error: you need to load the kernel first. Press any key to continue...

I tried also using the 'e' and 'c' keys off this menu; this brought into other menus (which are too much to type up) and on another menu where ^E and ^X can be used to 'edit' and 'execute' boot statements, none of which works correctly or is obvious what to alter or enter.

I also got into an interface with a 'grub>' prompt. I tried some of the grub commands, but had little clue what to do with that. E.g., "linuxefi /isolinux/isolinux.bin" returned "error: invalid magic number." Interesting, but not getting CentOS 7 booted.

Any know what else is possible?