[ipxe-devel] 486 with a Realtek 8139
n-a-zhubr at yandex.ru
Sat May 8 01:03:50 UTC 2021
I've finished with the subject successfully.
What I've done is using prot_to_real implementation in current iPXE, I
tried to mimic it as much as possible in respective place in Etherboot.
- use ljmp instead of lret (after cr0 change);
- assign ss and esp explicitely after that;
- assign all other segment registers explicitely.
Then Etherboot works fine on 486.
So iPXE's implementation is likely correct and supposedly it should work
too, as soon as all 586 opcodes are eliminated or handled carefully as
discussed previously. However my brain has pretty much exploded already
so I'm not going into more testing for now.
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