Re: [Qemu-devel] [PATCH 1/2] ahci: Fix CD-ROM signature

[John Snow <jsnow@redhat.com>]

On 07/06/2015 05:49 PM, John Snow wrote:
> From: Hannes Reinecke <hare@suse.de>
> 
> The CD-ROM signature is 0xeb140101, not 0xeb140000.
> Without this change OVMF/Duet runs into a timeout trying
> to detect a SATA cdrom.
> 
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  hw/ide/ahci.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/ide/ahci.h b/hw/ide/ahci.h
> index 9f5b4d2..68d5074 100644
> --- a/hw/ide/ahci.h
> +++ b/hw/ide/ahci.h
> @@ -166,7 +166,7 @@
>  #define AHCI_CMD_HDR_CMD_FIS_LEN           0x1f
>  #define AHCI_CMD_HDR_PRDT_LEN              16
>  
> -#define SATA_SIGNATURE_CDROM               0xeb140000
> +#define SATA_SIGNATURE_CDROM               0xeb140101
>  #define SATA_SIGNATURE_DISK                0x00000101
>  
>  #define AHCI_GENERIC_HOST_CONTROL_REGS_MAX_ADDR 0x20
> 

FWIW for review purposes, this is based on ATA8 AC3, Table 184 "Device
Signatures for Normal Output" and is very straightforward.

For how the component fields there (LBA and Count) become a single 4
byte signature, see AHCI 1.3 section 3.3.9 (PxSIG) and this is the value
we are emulating here with the #define.

I gave this patch a soft ACK in the past, but it feels wrong to give it
an R-B when I'm sending it out myself :)

--js