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Some embedded platforms have no keyboard controller. Give up waiting

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for it to react after a timeout.
This commit is contained in:
phk 2004-06-02 09:38:32 +00:00
parent 28dbdb7978
commit 36aa5c56d2
1 changed files with 11 additions and 4 deletions
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15
sys/boot/i386/boot2/boot1.S
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@ -197,13 +197,16 @@ main.5: mov %dx,MEM_ARG # Save args
xorb %al,%al # Zero assumed bss from
rep # the end of boot2.bin
stosb # up to 0x10000
callw seta20 # Enable A20
jmp start+MEM_JMP-MEM_ORG # Start BTX
/*
* Enable A20 so we can access memory above 1 meg.
* Use the zero-valued %cx as a timeout for embedded hardware which do not
* have a keyboard controller.
*/
seta20: cli # Disable interrupts
seta20.1: inb $0x64,%al # Get status
seta20.1: dec %cx # Timeout?
jz seta20.3 # Yes
inb $0x64,%al # Get status
testb $0x2,%al # Busy?
jnz seta20.1 # Yes
movb $0xd1,%al # Command: Write
@ -213,8 +216,12 @@ seta20.2: inb $0x64,%al # Get status
jnz seta20.2 # Yes
movb $0xdf,%al # Enable
outb %al,$0x60 # A20
seta20.3:
sti # Enable interrupts
retw # To caller
jmp start+MEM_JMP-MEM_ORG # Start BTX
/*
* Trampoline used to call read from within boot1.
*/