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UEFI and GPT (GUID Partition Table)
Dave Yeo:
os2boot and os2ldr as well, I guess for each file system that supports booting.
Roderick Klein:
--- Quote from: Dave Yeo on February 27, 2015, 10:35:13 pm ---os2boot and os2ldr as well, I guess for each file system that supports booting.
--- End quote ---
Hybrid MBR might be a solution but opinions seems to vary.
Roderick
Martin Iturbide:
About UEFI
I had been reading there are some kind of UEFI applications that has the UEFI keys that acts like launcher for other applications. I don't know if that idea can be used to run OS2-eCS on an "UEFI ENABLED" machine.
I had read that there is GRUB with UEFI support and something else called UEFI Shim loader.
But maybe I'm understanding it wrong. I don't know if someone has more experience on this subject and can share what they have researched.
Regards
ivan:
Martin, it might be a good idea for you to talk with Jan van Wijk (DFSee) about this. I think he would know much more than any of us.
walking_x:
About UEFI:
* on PC - it always 64-bit.
* it uses own interrupt handling for various things (USB keyboard, SATA devices, etc).
* it provides only graphic 32-bit modes, for all, including "console". Graphic functions are extremly slow. Modern graphic protocol can supply pointer to video memory, but this is optional.
* OS/2 kernel protected mode environment is incompatible with UEFI ... Also, UEFI uses 1st MB for own needs (GDT/IDT/page tables, etc) - but this space required for kernel too.This mean:
* we cannot use UEFI from kernel
* we cannot use any hardware until the end first boot stage (when our own BASEDEV drivers becomes ready).
* we cannot use BIOS int 10h, generally. Now it still present, but this is not guaranteed in the future. QEMU with TianoCore UEFI have no BIOS at all, for example. Therefore, the native video driver is also required!Boot process must be changed seriously:
* UEFI app loads all files for 1st boot stage (basedev drivers). Now this feature known as "preload" (in OS/4 kernel).
* exit from UEFI and switching PC back to real mode to start kernel.
* start basedev drivers (by using copy of it, was cached above). This requires some changes in boot file system or in kernel.
* there are a plenty of other problems, but main is video... GPT itself is easy to implement. But we have another one trouble here - sector number in all IOCTLs - 32-bit... I.e., disk i/o in OS/2 limited to 2Tb. There is no way to read data above this border.
So, David must design new IOCTLs and implement it in Danis/AHCI, then add changes to all disk i/o staff (DASD/LVM).
Even to implement huge disk splitting (3Tb -> 2Tb+1Tb) - like it was done in partflt - 1st stage still required (64-bit sector number in Danis).
And, yes, hybrid table can be used too, but this is dangerous and this "hack" limited to max of 3 (primary) partitions.
This is the picture - how I see it ;)
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