Timeline for How many EFI System Partitions (ESP) can a computer have?
Current License: CC BY-SA 3.0
12 events
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| Sep 1, 2021 at 13:16 | comment | added | Rod Smith | @ThorstenSchöning, the 13.3.3 section you yourself quote is quite explicit that the EFI spec does not impose a limit on the number of ESPs on a computer. The use of the word "the" preceding "System partition" is extraordinarily weak evidence to the contrary; you have to read a lot into the use of the word "the" to draw an inference contradicting what is explicitly stated elsewhere. The explicit statement easily trumps such an inference. References to multiple "conforming FAT partitions" are irrelevant to the discussion. | |
| Aug 31, 2021 at 6:21 | comment | added | Thorsten Schöning |
Afterwards I would have quoted sentences which obviously focus on a single ESP: System partition. The System partition defines a partition and file system that are designed to allow safe sharing[...]The ability to include a separate, sharable system partition presents an opportunity[...] The spec uses phrases like "the system partition" at many other places as well. And one argument from my links again: Further, UEFI implementations may allow the use of conforming FAT partitions which do not use the ESP GUID. So in practice things might simply be mixed.
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| Aug 31, 2021 at 6:15 | comment | added | Thorsten Schöning |
@RodSmith I never claimed that I quoted the spec. You didn't quote that as well. I confronted you with other opinions and expected you to e.g. quote sentences like the following: This will allow drivers and applications, including OS loaders, to easily search for handles that represent EFI System Partitions or vendor specific partition types. 13.3.3 Number and Location of System Partitions UEFI does not impose a restriction on the number or location of System Partitions that can exist on a system. uefi.org/sites/default/files/resources/UEFI_Spec_2_8_final.pdf
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| Aug 30, 2021 at 14:41 | comment | added | Rod Smith | No, @ThorstenSchöning, the link you provided is not the EFI spec and does not explicitly say that the number of ESPs is limited. The EFI spec itself, the last time I checked, did not say anything explicit about the number of ESPs permitted on a disk or on a computer. Your claim that I need to prove this is backwards. My claim is that this information is not present in the document, which is impossible to prove except by quoting the whole document. Your claim, OTOH, that there is an explicit limit in the EFI spec is easily demonstrated, if true; just quote or reference the passage. | |
| Aug 29, 2021 at 13:11 | comment | added | Thorsten Schöning |
@RodSmith Both links are of course explicit about how many ESP are allowed: No you really can't. There can only be one ESP and that's in the spec. and The parts of the spec you quoted are not referring explicitly to an ESP, but just "any recognized partition" which also includes non-ESP FAT32 partitions. So you are missing the point: It's your claim that the number is NOT limited, so you need to prove and didn't. My links provide good arguments that it's limited, so it's claim vs. claim, while my quoted ones are actually based on arguments.
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| Aug 28, 2021 at 14:55 | comment | added | Rod Smith | @ThorstenSchöning, the page you reference does not address the number of ESPs that are permitted on a computer or hard disk, just the distinction between an ESP and non-ESP FAT partitions and how the EFI discovers and uses partitions generally. What's more, that post is somebody's interpretation of the EFI specification (as is my answer here). If you wish to challenge my claim that the EFI specification does not limit the number of ESPs, please reference the part of the EFI specification that does so. If such a limit is in the EFI specification, quoting it is an easy refutation of my claim. | |
| Aug 27, 2021 at 6:20 | comment | added | Thorsten Schöning |
the EFI specification imposes no limit on the number of ESPs that may be present on a computer or on a hard disk Other people see that differently: news.ycombinator.com/item?id=16261695 news.ycombinator.com/item?id=16262177 One can have lots of FAT32 partitions, but not each of those is necessarily an ESP.
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| Oct 13, 2019 at 17:41 | comment | added | opatut | Windows 10 failed to install while I had a two disks with an ESP each. When I unplugged the other one, the installer was able to continue without error, reusing the existing ESP on the only disk I left plugged in (which included the target window root partition as well). | |
| Dec 15, 2013 at 20:16 | comment | added | Rod Smith | Regarding the quote that "access to a partition is controlled by the system firmware," you're over-interpreting. That doesn't refer to cryptographic controls, but to the fact that the EFI provides drivers to give EFI programs access to partitions. Microsoft does say that it supports just one ESP. For instance, here: "Q: Can there be two ESPs on a single disk? A: Such a configuration should not be created and is not supported in Windows." | |
| Dec 15, 2013 at 18:41 | vote | accept | jww | ||
| Dec 15, 2013 at 18:41 | comment | added | jww | Thanks Rod. "You're operating under the misapprehension that PKs are tied to ESPs". Microsoft states "Access to a partition is controlled by the system firmware before the system boots the operating system". How can the firmware limit access to a partition for a Boot Option if not by a particular Platform Key? I understand signing, but how about if PK1, PK2, etc are used as a principal in a simple ACL (I'm trying to figure out how the authz subsystem works here). | |
| Dec 15, 2013 at 17:42 | history | answered | Rod Smith | CC BY-SA 3.0 |