question about reserve_bios_regions

[Cao jin]

Hi,

  I am looking into these code via find_trampoline_placement, and I have
some questions still not clear after lots of investigation, hope to get
some hints.

1. How is the value of BIOS_START_MIN(128k) determined? I don't find any
clue about it until now.

2. BIOS_START_MAX is define as 0x9f000U(636k), but both the comments say
640k, is that a quirk or just typo?  I thought the 4k difference is the
quirk, but later I guess the real quirk lies in latter judgment of :

  if (ebda_start >= BIOS_START_MIN && ebda_start < bios_start)


I have checked out commit edce21216a8: ("x86/boot: Reorganize and clean
up the BIOS area reservation code"), still no clue.

-- 
Sincerely,
Cao jin