From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:39205)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <dl.soluz@gmx.net>) id 1ZKRpL-0002yU-Dn
	for qemu-devel@nongnu.org; Wed, 29 Jul 2015 09:55:24 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <dl.soluz@gmx.net>) id 1ZKRpG-0006RX-Dd
	for qemu-devel@nongnu.org; Wed, 29 Jul 2015 09:55:23 -0400
Received: from mout.gmx.net ([212.227.17.22]:51857)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <dl.soluz@gmx.net>) id 1ZKRpG-0006RN-3f
	for qemu-devel@nongnu.org; Wed, 29 Jul 2015 09:55:18 -0400
References: <55B734A7.8040108@gmx.net>
	<CAMO55fmd4YMCk-BMBE5PjsBzUAiggo0Op_6=epwfM8VQJPksCA@mail.gmail.com>
	<55B8B122.7020406@gmx.net>
	<CAMO55fmbRSyhLbFKPiyH9RWH3GszNCsAj4nePYSTm2Tt5DhdEA@mail.gmail.com>
From: Dennis Luehring <dl.soluz@gmx.net>
Message-ID: <55B8DB46.6070307@gmx.net>
Date: Wed, 29 Jul 2015 15:55:18 +0200
MIME-Version: 1.0
In-Reply-To: <CAMO55fmbRSyhLbFKPiyH9RWH3GszNCsAj4nePYSTm2Tt5DhdEA@mail.gmail.com>
Content-Type: text/plain; charset=iso-8859-15; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] Debian 7.8.0 SPARC64 on qemu - anything i can do
 to speedup the emulation?
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Karel Gardas <gardask@gmail.com>
Cc: qemu-devel@nongnu.org

Am 29.07.2015 um 14:34 schrieb Karel Gardas:
>   Once it boots, tell me how to find the asnwers to your
> questions.

compile with gcc test.cpp and run

-----------
#include <stdint.h>
#include <stdio.h>
#include <stddef.h>
#include <string.h>
#include <assert.h>

int main()
{
   uint16_t value = 0x1234;

   {
     volatile uint8_t* ptr = (uint8_t*)&value;
     printf("endianess: %s\n", ptr[0]==0x34 ? "little":"big");
   }

   uint8_t buffer[1+sizeof(value)]={0};
   uint8_t* ptr = buffer;
   if(ptrdiff_t(ptr) % 2 == 0)
   {
     ++ptr;
   }
   uint16_t* unaligned_word = (uint16_t*)ptr;

   ::memcpy(unaligned_word, &value, sizeof(value));

   printf("try to access unaligned word\n");
   uint16_t read = *unaligned_word; // here can happen Bus-Errors, 
Exceptions, whatever your architecture likes
   printf("  equal to 0x%04X: %s\n", value, read == value ? 
"YES":"!!NO!!"); // sometimes you get the value - but its still wrong
   printf("  value: 0x%04X\n", read);
   printf("done\n");

   return 0;
}
-----------