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[prefix] Call decompressor in flat real mode when DEBUG=libprefix is enabled

Allow the decompressor the option of generating debugging output via
the BIOS console by calling it in flat real mode (rather than 16-bit
protected mode) when libprefix.S is built with debugging enabled.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
tags/v1.20.1
Michael Brown vor 9 Jahren
Ursprung
Commit
93178adb98
1 geänderte Dateien mit 16 neuen und 0 gelöschten Zeilen
  1. 16
    0
      src/arch/i386/prefix/libprefix.S

+ 16
- 0
src/arch/i386/prefix/libprefix.S Datei anzeigen

@@ -394,8 +394,10 @@ process_bytes:
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 	movw	%ax, %fs
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 	movw	%ax, %gs
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+#ifdef NDEBUG
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 	/* Call memcpy()-like function */
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 	call	*%bx
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+#endif
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 	/* Return to (flat) real mode */
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 	movl	%cr0, %eax
@@ -409,6 +411,20 @@ process_bytes:
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 	popw	%fs
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 	popw	%gs
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+#ifndef NDEBUG
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+	/* Call memcpy()-like function in flat real mode (to allow for
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+	 * debug output via INT 10).
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+	 */
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+	pushw	%ds
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+	pushw	%es
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+	xorw	%ax, %ax
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+	movw	%ax, %ds
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+	movw	%ax, %es
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+	call	*%bx
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+	popw	%es
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+	popw	%ds
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+#endif
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+
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 	/* Restore GDT */
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 	data32 lgdt -8(%bp)
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 	addw	$( 8 /* saved GDT */ + ( PM_DS + 8 ) /* GDT on stack */ ), %sp

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