From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [PATCH kvm-unit-tests 2/2] realmode: print to serial port
Date: Thu, 9 May 2013 17:26:39 +0300
Message-ID: <20130509142639.GS12349@redhat.com>
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 <1368109414-6458-3-git-send-email-pbonzini@redhat.com>
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Cc: kvm@vger.kernel.org
To: Paolo Bonzini <pbonzini@redhat.com>
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On Thu, May 09, 2013 at 04:23:34PM +0200, Paolo Bonzini wrote:
> The realmode test is still printing to the old debug port at 0xf1.
> Use the serial port instead.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  x86/realmode.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 63 insertions(+), 2 deletions(-)
> 
> diff --git a/x86/realmode.c b/x86/realmode.c
> index 71c8a7d..67582b5 100644
> --- a/x86/realmode.c
> +++ b/x86/realmode.c
> @@ -1,3 +1,7 @@
> +#ifndef USE_SERIAL
> +#define USE_SERIAL
> +#endif
> +
>  asm(".code16gcc");
>  
>  typedef unsigned char u8;
> @@ -22,16 +26,73 @@ static int strlen(const char *str)
>  	return n;
>  }
>  
> +static void outb(u8 data, u16 port)
> +{
> +	asm volatile("out %0, %1" : : "a"(data), "d"(port));
> +}
> +
> +#ifdef USE_SERIAL
> +static int serial_iobase = 0x3f8;
> +static int serial_inited = 0;
It is never set to 1. The same is in the file this is copied from.
Noticed it while trying to do the same.

> +
> +static u8 inb(u16 port)
> +{
> +	u8 data;
> +	asm volatile("in %1, %0" : "=a"(data) : "d"(port));
> +	return data;
> +}
> +
> +static void serial_outb(char ch)
> +{
> +	u8 lsr;
> +
> +	do {
> +		lsr = inb(serial_iobase + 0x05);
> +	} while (!(lsr & 0x20));
> +
> +	outb(ch, serial_iobase + 0x00);
> +}
> +
> +static void serial_init(void)
> +{
> +	u8 lcr;
> +
> +	/* set DLAB */
> +	lcr = inb(serial_iobase + 0x03);
> +	lcr |= 0x80;
> +	outb(lcr, serial_iobase + 0x03);
> +
> +	/* set baud rate to 115200 */
> +	outb(0x01, serial_iobase + 0x00);
> +	outb(0x00, serial_iobase + 0x01);
> +
> +	/* clear DLAB */
> +	lcr = inb(serial_iobase + 0x03);
> +	lcr &= ~0x80;
> +	outb(lcr, serial_iobase + 0x03);
> +}
> +#endif
> +
>  static void print_serial(const char *buf)
>  {
>  	unsigned long len = strlen(buf);
> -
> +#ifdef USE_SERIAL
> +	unsigned long i;
> +	if (!serial_inited) {
> +	    serial_init();
> +	}
> +
> +	for (i = 0; i < len; i++) {
> +	    serial_outb(buf[i]);
> +	}
> +#else
>  	asm volatile ("addr32/rep/outsb" : "+S"(buf), "+c"(len) : "d"(0xf1));
> +#endif
>  }
>  
>  static void exit(int code)
>  {
> -        asm volatile("out %0, %1" : : "a"(code), "d"((short)0xf4));
> +	outb(code, 0xf4);
>  }
>  
>  struct regs {
> -- 
> 1.8.1.4
> 
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--
			Gleb.