[Qemu-devel] target_phys_addr_t definition

[Qemu-devel] target_phys_addr_t definition

[Johannes Luber]

Hi,

I've been looking through the sources and stumbled over targphys.h, which contains:

/* target_phys_addr_t is the type of a physical address (its size can
   be different from 'target_ulong'). We have sizeof(target_phys_addr)
   = max(sizeof(unsigned long),
   sizeof(size_of_target_physical_address)) because we must pass a
   host pointer to memory operations in some cases */

#if TARGET_PHYS_ADDR_BITS == 32
typedef uint32_t target_phys_addr_t;
#define TARGET_PHYS_ADDR_MAX UINT32_MAX
#define TARGET_FMT_plx "%08x"
#elif TARGET_PHYS_ADDR_BITS == 64
typedef uint64_t target_phys_addr_t;
#define TARGET_PHYS_ADDR_MAX UINT64_MAX
#define TARGET_FMT_plx "%016" PRIx64
#endif

The comment says "sizeof(target_phys_addr) = max(...)" yet I don't the actual definition depending on the host at all. This means that on 64 bit hosts things are going wrong. sizeof(uint32_t) will be always 4 and actually using sizeof(unsigned long) will still result on 64-bit Windows in 4, despite pointer having 8 bytes.

As the comment remarks this won't work with physical pointers which reference pages beyond the 4 GB limit (unless the pointers don't have always some high bits set). So my question is: Does Qemu support 64-bit compilation for hosts correctly?

Best regards,
Johannes
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[Qemu-devel] Re: target_phys_addr_t definition

[Johannes Luber]

> "Johannes Luber" <JALuber@gmx.de> wrote:
...
> So my question is: Does Qemu support 64-bit compilation
> for hosts correctly?
> >
> > Best regards,
> > Johannes
> 
> Dragons here.
> 
> See configure, the interesting bit is:
> 
> if [ $target_phys_bits -lt $hostlongbits ] ; then
>   target_phys_bits=$hostlongbits
> fi
> 
> TARGET_PHYS_ADDR_BITS is the maximum of host + target long sizes.
> 
> Later, Juan.

Thanks for the quick response! It seems that someone edited my local config.h which resulted in losing the config-host.h. It would be nice if something like

#ifndef HOST_LONG_BITS
#error No HOST_LONG_BITS
#endif

could be included at appropriate places. This would make this problem self-evident in the future.

Best regards,
Johannes
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