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From: Dennis Luehring <dl.soluz@gmx.net>
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Date: Thu, 30 Jul 2015 05:47:19 +0200
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Subject: Re: [Qemu-devel] Debian 7.8.0 SPARC64 on qemu - anything i can do
 to speedup the emulation?
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To: Karel Gardas <gardask@gmail.com>
Cc: qemu-devel@nongnu.org

so your aarch64 is just less todo for qemu - not EVERY >= 16bit memory 
access needs swapping or needs check for unaligned access to emulate 
bus-erros

Am 29.07.2015 um 16:41 schrieb Karel Gardas:
> ubuntu@ubuntu:~$ ./a.out
> endianess: little
> try to access unaligned word
>    equal to 0x1234: YES
>    value: 0x1234
> done
>
> On Wed, Jul 29, 2015 at 3:55 PM, Dennis Luehring <dl.soluz@gmx.net> wrote:
> > 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;
> > }
> > -----------
> >