Friday, January 23, 2015

UEFI Where is the boot code and GUID partition table stored?



I'm reading this article and I'm very confused over what the autor sais in the section "Managing partitions and security: BIOS vs UEFI"



quote:





Unlike BIOS, UEFI stores in the firmware itself both the boot code and
a GUID partition table




I thought the boot code is stored in EFI system partition, and GUID partition table is stored on hard drive that is in GPT partition table, but the author claims both of these are stored in UEFI firmware, can anybody confirm this odd statement and also please if possible (not required) provide reference to some good article about UEFI boot process.


Answer



That quote is nonsense, and the article itself contradicts it later on. The partition table is always stored on the disk itself (doing otherwise would make the disk difficult to use).



UEFI systems do contain a few more things in firmware which BIOS used to read from disk; e.g. the firmware-provided boot menu which holds configuration in NVRAM and lets you choose from multiple installed bootloaders / operating systems – I suspect this is where the author's confusion comes from.




(Also, note that Secure Boot is a relatively recent feature – many older UEFI systems do not have it.)


No comments:

Post a Comment

linux - How to SSH to ec2 instance in VPC private subnet via NAT server

I have created a VPC in aws with a public subnet and a private subnet. The private subnet does not have direct access to external network. S...