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A comment on Intel mulls cutting 16 and 32-bit support, booting straight into 64-bit mode. Parent comment

Re:Intel mulls cutting 16 and 32-bit support, booting straig... by t0b1 on Thursday May 25, 2023 @02:43PM (#36074436)
How so? The bootloader already runs in long mode with UEFI and it also takes care of bringing up other cores so this is not really a problem in my experience.
[ Parent | on HN ]
Re:Intel mulls cutting 16 and 32-bit support, booting straig... by monocasa on Thursday May 25, 2023 @03:20PM (#36074900)
UEFI doesn't really take care of bringing up the other cores. There's a way to get access to them, but you have to give them back to UEFI before exiting boot services, so that doesn't really help your kernel. You still need to do the SIPI into x86-16 code to really take control of the AP cores.

Even the new way (that isn't actually implemented AFAIK) just SIPIs into long mode code, it doesn't use the UEFI multicore stuff.

[ Parent | on HN ]
Re:Intel mulls cutting 16 and 32-bit support, booting straig... by JoshTriplett on Thursday May 25, 2023 @03:18PM (#36074868)
Linux still needs to use a Startup IPI to bring up other CPUs, which starts them running in 16-bit mode at an address under 1MB.

Having a fully 64-bit way to bring up other CPUs would simplify that.

[ Parent | on HN ]