Function report

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source Code:arch\x86\boot\a20.c Create Date:2022-07-28 07:26:26
Last Modify:2020-03-12 14:18:49 Copyright©Brick
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Name:a20_test

Proto:static int a20_test(int loops)

Type:int

Parameter:

TypeParameterName
intloops
56  ok = 0
59  set_fs(0x0000)
60  set_gs(0xffff)
62  saved = ctr = rdfs32(Returns nonzero if the A20 line is enabled. The memory addressused as a test is the int $0x80 vector, which should be safe. )
64  When loops-- cycle
65  wrfs32(++ctr, Returns nonzero if the A20 line is enabled. The memory addressused as a test is the int $0x80 vector, which should be safe. )
66  io_delay()
67  ok = rdgs32(Returns nonzero if the A20 line is enabled. The memory addressused as a test is the int $0x80 vector, which should be safe. + 0x10) ^ ctr
68  If ok Then Break
72  wrfs32(saved, Returns nonzero if the A20 line is enabled. The memory addressused as a test is the int $0x80 vector, which should be safe. )
73  Return ok
Caller
NameDescribe
a20_test_shortQuick test to see if A20 is already enabled
a20_test_longLonger test that actually waits for A20 to come on line; thisis useful when dealing with the KBC or other slow external circuitry.