[Qemu-devel] sparc esp NetBSD-guest "sd3: mode sense (4) returned nonsense"

[Artyom Tarasenko <atar4qemu@googlemail.com>]

>From NetBSD source, it looks like HDD geometry detection should work
under qemu: they call "mode sense" and "read capacity", and both
commands are implemented in qemu's hw/scsi-disk.h. It doesn't work
though, so NetBSD has to fabricate a disk geometry.

To make debugging easier I tried to boot an older version - NetBSD
1.3.3. And put some extra debugging in esp.c:

static uint32_t get_cmd(ESPState *s, uint8_t *buf)
{
    uint32_t dmalen;
    int target;

    target = s->wregs[ESP_WBUSID] & BUSID_DID;
    if (s->dma) {
        dmalen = s->rregs[ESP_TCLO] | (s->rregs[ESP_TCMID] << 8);
        s->dma_memory_read(s->dma_opaque, buf, dmalen);
    } else {
        dmalen = s->ti_size;
        memcpy(buf, s->ti_buf, dmalen);
printf("NON-DMA rptr %d, wptr %d %2x (0) %2x %2x %2x %2x\n",
s->ti_rptr, s-> ti_wptr, buf[0],buf[1], buf[2],buf[3], buf[4]);
        buf[0] = 0;
    }

qemu-system-sparc -M SS-20 -nographic  -hda ~/sparc/miniroot-133.fs -m 64
...
NON-DMA rptr 0, wptr 1 c0 (0)  0  0 1a  0
Set ATN & Stop: cmdlen 3
scsi-disk: Command: lun=0 tag=0x0 data=0x00 0x00 0x1a 0x00 0x04 0x00
scsi-disk: Test Unit Ready
scsi-disk: Command complete tag=0x0 status=0 sense=0
sd3: mode sense (4) returned nonsense; using fictitious geometry


NetBSD sent command "0x1a" via Set ATN & Stop, but it for some reason
the command got padded and disk got "0x0 0x0 0x1a", no wonder that its
output looks like a non-sense to NetBSD.

Any ideas why does it happen?