(gdb) p *qiov
$11 = {iov = 0x7f647c76d840, niov = 1, {{nalloc = 1, local_iov = {iov_base =
0x0,
iov_len = 512}}, {__pad = "\001\000\000\000\000\000\000\000\000\000\000",
size = 512}}}
(gdb) bt
#0 blk_aio_pwritev (blk=0x5595ae2c6c30, offset=0, qiov=0x7f6420802070, flags=0,
cb=0x5595ace6f0b0 <dma_blk_cb>, opaque=0x7f6420802010)
at ../block/block-backend.c:1682
#1 0x00005595ace6f185 in dma_blk_cb (opaque=0x7f6420802010, ret=<optimized
out>)
at ../softmmu/dma-helpers.c:179
#2 0x00005595ace6f778 in dma_blk_io (ctx=0x5595ae0609f0,
sg=sg@entry=0x5595af694d00, offset=offset@entry=0, align=align@entry=512,
io_func=io_func@entry=0x5595ace6ee30 <dma_blk_write_io_func>,
io_func_opaque=io_func_opaque@entry=0x5595ae2c6c30,
cb=0x5595acd40b30 <ide_dma_cb>, opaque=0x5595af6949d0,
dir=DMA_DIRECTION_TO_DEVICE) at ../softmmu/dma-helpers.c:244
#3 0x00005595ace6f90a in dma_blk_write (blk=0x5595ae2c6c30,
sg=sg@entry=0x5595af694d00, offset=offset@entry=0, align=align@entry=512,
cb=cb@entry=0x5595acd40b30 <ide_dma_cb>,
opaque=opaque@entry=0x5595af6949d0)
at ../softmmu/dma-helpers.c:280
#4 0x00005595acd40e18 in ide_dma_cb (opaque=0x5595af6949d0, ret=<optimized
out>)
at ../hw/ide/core.c:953
#5 0x00005595ace6f319 in dma_complete (ret=0, dbs=0x7f64600089a0)
at ../softmmu/dma-helpers.c:107
#6 dma_blk_cb (opaque=0x7f64600089a0, ret=0) at ../softmmu/dma-helpers.c:127
#7 0x00005595ad12227d in blk_aio_complete (acb=0x7f6460005b10)
at ../block/block-backend.c:1527
#8 blk_aio_complete (acb=0x7f6460005b10) at ../block/block-backend.c:1524
#9 blk_aio_write_entry (opaque=0x7f6460005b10) at ../block/block-backend.c:1594
#10 0x00005595ad258cfb in coroutine_trampoline (i0=<optimized out>,
i1=<optimized out>) at ../util/coroutine-ucontext.c:177