Currently we set them to 512 bytes unless manually specified. Unforuntaly some brain-dead partitioning tools create unaligned partitions if they get low enough optiomal I/O size values, so don't report any at all unless explicitly set.
Signed-off-by: Christoph Hellwig <h...@lst.de> Index: qemu/block_int.h =================================================================== --- qemu.orig/block_int.h 2010-07-23 09:26:07.660494681 +0200 +++ qemu/block_int.h 2010-07-23 09:26:20.323494685 +0200 @@ -243,7 +243,7 @@ static inline unsigned int get_physical_ _conf.logical_block_size, 512), \ DEFINE_PROP_UINT16("physical_block_size", _state, \ _conf.physical_block_size, 512), \ - DEFINE_PROP_UINT16("min_io_size", _state, _conf.min_io_size, 512), \ - DEFINE_PROP_UINT32("opt_io_size", _state, _conf.opt_io_size, 512) + DEFINE_PROP_UINT16("min_io_size", _state, _conf.min_io_size, 0), \ + DEFINE_PROP_UINT32("opt_io_size", _state, _conf.opt_io_size, 0) #endif /* BLOCK_INT_H */