[Qemu-devel] qemu in full emulation on win32

[Alexey Kardashevskiy <aik@ozlabs.ru>]

Hi!

Found 2 problems while I was debugging qemu/ppc64-softmmu/qemu-system-ppc64.exe
WindowsXP SP3 Pro, 32bit, i686-pc-mingw32-gcc (GCC) 4.5.2.


1. The size of the following is 7 bytes on linux and 8 bytes on Windows:
struct {
    uint32_t hi;
    uint64_t child;
    uint64_t parent;
    uint64_t size;
} __attribute__((packed)) ranges[];

The structure is used between QEMU and Open Firmware (powerpc bios) so it is important.

The Feature is described here:
http://stackoverflow.com/questions/7789668/why-would-the-size-of-a-packed-structure-be-different-on-linux-and-windows-when
Shortly there is packing and ms-packing and they are different :)

The solutions are:
1. Add MS-specific #pragma pack(push,1) and #pragma pack(pop).
2. Add -mno-ms-bitfields (gcc >= 4.7.0)
3. Change the structure above to use only uint32_t.

What is the common way of solving such problems in QEMU?


2. QEMU cannot allocate 1024MB for the guest RAM. Literally, VirtualAlloc() fails on 1024MB BUT it does not if I allocate 1023MB and 64MB by 2 subsequent calls. We allocate RAM via memory_region_init_ram(). I am pretty sure this is not happening on 64bit Windows and I suspect that it is happening with qemu-system-x86.exe, is not it?

Do we care that there is actually enough RAM and we could allocate it in several chunks?



-- 
Alexey