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by pudquick
4114 days ago
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One piece that was not mentioned is the necessity of your UEFI / EFI implementation including integrated chipset driver support for talking to various devices (mass storage, USB, etc) at boot. Additionally how that can interact with legacy Option ROMs. It also didn't cover the replacement of the BIOS VGA baseline graphical communication standard with GOP (Graphics Output Protocol) - meaning that your graphics card itself specifically needs to be compatible with UEFI / EFI to even boot. I'm sad he took a negative stance to Apple in the article. Their implementation (of EFI) is very interesting in the choices they made and it's worth noting the differences (they do not, for instance, provide a graphical configuration choice "boot menu" like most PCs - they only provide visual boot media selection). Another interesting thing Apple did was, prior to all Windows editions natively booting to UEFI / EFI, they still wanted to provide dual boot support for OS X and Windows on their Intel Macs. But this meant that while OS X was EFI booting and required GPT drives - Windows was BIOS booting and required MBR drives. As such, Apple used a hybrid GPT/MBR format where the partition maps in both were in synchronization and GPT reserved the areas where MBR information was stored on the drive. |
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Good: No firmware setup UI. Leave the user out of it.
Good: Firmware built-in GUI boot manager that discovers currently bootable OS's dynamically. Plug in an external, an icon appears with an animated reveal. Animation in the f'n firmware built-in boot manager.
Bad: That boot manager hard wires a label "Windows" for any legacy CSM-BIOS installed OS, even if it isn't Windows.
Mixed: Apple's firmware is mainly based on Intel 1.10, with some extensions such as UEFI GOP, and some Apple stuff. It's not a standard UEFI 2.x firmware at all, and it's not documented at all. 3rd party bootloader programs have to have physical access to Macs to poke them with a stick in order to figure out how they work due to Apple's closed nature. So if you care about running open source OS's on Apple hardware, this is probably more "bad" than "mixed".
Very bad: There's a long standing pernicious bug with Disk Utility, on Boot Camp'd drives (OS X + Windows) which permits the user to resize the OS X volume thereby creating a 5th partition: ESP, OS X, New Partition, Apple Boot, Windows. And Apple's tools remove the hybrid MBR, replace it with a protective MBR, and now Windows is unbootable. All without warning. This behavior violates their own proscription against manipulating drives with hybrid MBRs. Technote 2166: "If block 0 contains any other form of MBR, it should refuse to manipulate the disk." Their message boards have hundreds of such complaints. This isn't new, it's been a problem for years, it was bug reported years ago, and Apple basically blamed it on Windows rather than their own tool which actually causes the problem by wiping out the PMBR. https://developer.apple.com/library/mac/technotes/tn2166/_in...
So I'm not a fan of their hybrid MBR hack, even though earlier on it was probably unavoidable. Windows has supported UEFI booting since Vista, but Apple's kinda dragged their feet on supporting UEFI Windows boot until very recently, and I'm not even certain Boot Camp Assistant defaults to this behavior yet.