On Thu, May 24, 2018 at 02:55:26PM +0000, Grant Likely wrote: > Personally I think we should encourage separate ESP and firmware partitions.
I'm still on the fence TBH... but whichever way we go I don't think it will contradict anything introduced by this patch. That leaves me inclined to post a github issue and then spin a v2 without mentioning this. Daniel. > ________________________________ > From: Alexander Graf <[email protected]> > Sent: Thursday, May 24, 2018 2:00:54 PM > To: Daniel Thompson > Cc: Grant Likely; [email protected]; arm.ebbr-discuss > Subject: Re: [Arm.ebbr-discuss] [PATCH] Describe protective partitioning for > platforms using shared storage > > > > On 24.05.18 11:16, Daniel Thompson wrote: > > On Wed, May 23, 2018 at 04:08:52PM +0200, Alexander Graf wrote: > >>>>> +MBR partitioning > >>>>> +^^^^^^^^^^^^^^^^ > >>>>> + > >>>>> +Protective partitions should have a partition type of 0xF8 unless some > >>>>> +immutable feature of the platform makes this impossible. > >>>> I'd like to be rid of the caveat here too, but there is a lot more > >>>> legacy to support with MBR. > >>> The known behaviour wiki mentions that RPi dictates 0x0C. > >> > >> On the RPI we simply use the ESP as firmware partition, so we don't have > >> any > >> need for a protective partition there. > > > > Hmmnnnn... this moves towards one of Grants' comments on the need to > > follow up my work with some rules about managing the ESP. Specifically > > what tells the OS that formatting the ESP will delete vital firmware > > (normally it only destroys other OS and firmware *extensions*). > > Firmware extensions may well be a driver necessary to actually boot the > system. I'd be very surprised if any installer thought it was a good > idea to remove the ESP. And if they do, it must be considered bad behavior. > > >> So maybe we could just allow the ESP to have type 0xC instead of 0xEF if > >> dictated by firmware? That should cover all cases except for Altera then > >> which has its bootloader in a 0xAF or so partition. > > > > I think I'm OK with this. > > > > Do we *have* to specify the alternative partition type is 0x0C or can we > > rely on searching for the EFI/ directory of FAT partitions when no other > > ESP presents itself? I admit I'm struggling a little to see how the > > pieces fit together but there are definitely clues that firmware might > > choose to searching for the EFI directory (albeit for GPT rather than > > MBR): > > > > "UEFI implementations may allow the use of conforming FAT partitions > > which do not use the ESP GUID. Partition creators may prevent UEFI > > firmware from examining and using a specific partition by setting bit > > 1 of the Partition Attributes" > > I think what our ESP search order should be is: > > * ESP GUID / ESP MBR partition ID > * All partitions marked with bootable flag > > That should cover all cases IMHO. > > > Alex > IMPORTANT NOTICE: The contents of this email and any attachments are > confidential and may also be privileged. If you are not the intended > recipient, please notify the sender immediately and do not disclose the > contents to any other person, use it for any purpose, or store or copy the > information in any medium. Thank you. _______________________________________________ boot-architecture mailing list [email protected] https://lists.linaro.org/mailman/listinfo/boot-architecture
