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fix stage2.asm: disk reads wait for BSY

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vmttmv
2025-12-30 05:08:54 +02:00
parent caea475daf
commit 09c48c2f50
1 changed files with 15 additions and 6 deletions
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21
bootloader/stage2.asm
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@@ -40,6 +40,13 @@ ata_lba_read:
push edx push edx
push edi push edi
; Wait BSY=0 before proceeding to write the regs
.wait_rdy:
mov edx, 0x1F7
in al, dx
test al, 0x80
jnz .wait_rdy
mov eax, [ebp+8] ; arg #1 = LBA mov eax, [ebp+8] ; arg #1 = LBA
mov cl, [ebp+12] ; arg #2 = # of sectors mov cl, [ebp+12] ; arg #2 = # of sectors
mov edi, [ebp+16] ; arg #3 = buffer address mov edi, [ebp+16] ; arg #3 = buffer address
@@ -74,21 +81,23 @@ ata_lba_read:
mov al, 0x20 ; Read with retry. mov al, 0x20 ; Read with retry.
out dx, al out dx, al
mov bl, cl ; Save # of sectors in BL mov bl, cl ; Save # of sectors in BL
.wait_drq: .wait_rdy2:
mov edx, 0x1F7 mov edx, 0x1F7
.do_wait_drq: .do_wait_rdy2:
in al, dx in al, dx
test al, 8 ; the sector buffer requires servicing. test al, 0x80 ; BSY?
jz .do_wait_drq ; keep polling until the sector buffer is ready. jnz .do_wait_rdy2
test al, 0x8 ; DRQ?
jz .do_wait_rdy2
mov edx, 0x1F0 ; Data port, in and out mov edx, 0x1F0 ; Data port, in and out
mov ecx, 256 mov ecx, 256
rep insw ; in to [RDI] rep insw ; in to [RDI]
dec bl ; are we... dec bl ; are we...
jnz .wait_drq ; ...done? jnz .wait_rdy2 ; ...done?
pop edi pop edi
pop edx pop edx