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Re: [Qemu-devel] [PATCH v1 1/1] scsi-disk: Block Device Characteristics
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v1 1/1] scsi-disk: Block Device Characteristics emulation fix |
Date: |
Thu, 12 Jul 2018 16:53:32 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
On 11/07/2018 22:58, Daniel Henrique Barboza wrote:
> The current BDC VPD page (page 0xb1) is too short. This can be
> seen running sg_utils:
>
> $ sg_vpd --page=bdc /dev/sda
> Block device characteristics VPD page (SBC):
> Block device characteristics VPD page length too short=8
>
> By the SCSI spec, the expected size of the SBC page is 0x40.
> There is no telling how the guest will behave with a shorter
> message - it can ignore it, or worse, make (wrong)
> assumptions.
>
> This patch fixes the emulation by setting the size to 0x40.
> This is the output of the previous sg_vpd command after
> applying it:
>
> $ sg_vpd --page=bdc /dev/sda -v
> inquiry cdb: 12 01 b1 00 fc 00
> Block device characteristics VPD page (SBC):
> [PQual=0 Peripheral device type: disk]
> Medium rotation rate is not reported
> Product type: Not specified
> WABEREQ=0
> WACEREQ=0
> Nominal form factor not reported
> FUAB=0
> VBULS=0
>
> To improve readability, this patch also adds the VBULS value
> explictly and add comments on the existing fields we're
> setting.
>
> Signed-off-by: Daniel Henrique Barboza <address@hidden>
Kevin kindly agreed to take this through the block tree, so
Acked-by: Paolo Bonzini <address@hidden>
Thanks,
Paolo
> ---
> hw/scsi/scsi-disk.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index 32f3f96ff8..5ae7baa082 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -775,11 +775,12 @@ int scsi_disk_emulate_vpd_page(SCSIRequest *req,
> uint8_t *outbuf)
> }
> case 0xb1: /* block device characteristics */
> {
> - buflen = 8;
> + buflen = 0x40;
> outbuf[4] = (s->rotation_rate >> 8) & 0xff;
> outbuf[5] = s->rotation_rate & 0xff;
> - outbuf[6] = 0;
> - outbuf[7] = 0;
> + outbuf[6] = 0; /* PRODUCT TYPE */
> + outbuf[7] = 0; /* WABEREQ | WACEREQ | NOMINAL FORM FACTOR */
> + outbuf[8] = 0; /* VBULS */
> break;
> }
> case 0xb2: /* thin provisioning */
>