Hi, On 10/10/19 8:53 PM, Dr. David Alan Gilbert wrote: > * Auger Eric (eric.au...@redhat.com) wrote: >> Hi peter, >> >> On 10/10/19 2:35 PM, Peter Xu wrote: >>> On Thu, Oct 10, 2019 at 02:11:46PM +0200, Auger Eric wrote: >>>>>>> Also, should we avoid using UINT in all cases? But of course if we >>>>>>> start to use VMSTATE_UINT32_V then we don't have this issue. >>>>>> Depending on the clarification of above point, maybe I can rename >>>>>> VMSTATE_GTREE_DIRECT_KEY_V into VMSTATE_GTREE_DIRECT_UINT_KEY_V >>>>>> >>>>>> direct keys seem to be more common for hash tables actually. >>>>>> https://developer.gnome.org/glib/stable/glib-Hash-Tables.html#g-hash-table-new-full >>>>>> >>>>>> There are stand conversion macros to/from int, uint, size >>>>>> https://developer.gnome.org/glib/stable/glib-Type-Conversion-Macros.html >>>>> >>>>> Yeh it's fine to use direct keys. Though my question was more about >>>>> "unsigned int" - here when we put, we cast a pointer into unsigned >>>>> int, which can be 2/4 bytes, IIUC. I'm thinking whether at least we >>>>> should use direct cast (e.g., (uint32_t)ptr) to replace >>>>> GPOINTER_TO_UINT() to make sure it's 4 bytes. Futher, maybe we should >>>>> start with uint64_t here in the migration stream, otherwise we should >>>>> probably drop the high 32 bits if we migrate a gtree whose key is 64 >>>>> bits long (and since we're working with migration we won't be able to >>>>> change that in the future for compatibility reasons...). >>>>> >>>>> Summary: >>>>> >>>>> Maybe we can replace: >>>>> >>>>> qemu_put_be32(f, GPOINTER_TO_UINT(key)); /* direct key */ >>>>> >>>>> To: >>>>> >>>>> qemu_put_be64(f, (uint64_t)key); /* direct key */ >>>>> >>>>> And apply similar thing to get() side? >>>> >>>> This was my first idea as well but I got stuck with a mingw compilation >>>> issues if I remember correctly, trying to cast pointers to a wrong sized >>>> uint. This got removed by using the GPOINTER_TO_UINT conversion functions. >>> >>> #define GPOINTER_TO_UINT(p) ((guint) (gulong) (p)) >>> >>> Could "(uint64_t)(uintptr_t)pointer" do the work? >> the problem rather is on the get side, when you cast the uint64_t value >> into the pointer. it does not compile with >> >> make docker-test-mingw@fedora >> >> >> /tmp/qemu-test/src/migration/vmstate-types.c:800:19: error: cast to >> pointer from integer of different size [-Werror=int-to-pointer-cast] >> key = (void *)(uint64_t)qemu_get_be64(f); >> >> I would be tempted to rename the macro to emphasize the key is an >> uint32. It should cover most of the use cases, no? > > Try: > (void *)(uintptr_t)qemu_get_be64(f) This indeed compiles with mingw. Thanks to both of you for the hint. I was not familiar with uintptr_t.
Thanks Eric > > >> >> Thanks >> >> Eric >> >> >>> >>> Thanks, >>> > -- > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK >