From: Kevin Wolf <kwolf@redhat.com>
To: Alexander Graf <agraf@suse.de>
Cc: "Stefan Weil (commit_signer:2/19=11%)" <sw@weilnetz.de>,
"Anthony Liguori (commit_signer:6/19=32%)" <aliguori@us.ibm.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"\"Andreas Färber (commit_signer:2/19=11%)\"" <afaerber@suse.de>,
"Daniel Verkamp" <daniel@drv.nu>
Subject: Re: [Qemu-devel] [PATCH] ahci: SATA FIS is 20 bytes, not 0x20
Date: Wed, 23 May 2012 12:04:03 +0200 [thread overview]
Message-ID: <4FBCB613.1040901@redhat.com> (raw)
In-Reply-To: <78A9AA1C-331F-4421-99AE-3D2DE9AEBFF2@suse.de>
Am 23.05.2012 11:53, schrieb Alexander Graf:
>
>
> Am 23.05.2012 um 11:13 schrieb Kevin Wolf <kwolf@redhat.com>:
>
>> Am 23.05.2012 01:26, schrieb Daniel Verkamp:
>>> As in the SATA and AHCI specifications, a FIS is 5 Dwords of 4 bytes
>>> each, which comes to 20 bytes (decimal), not 0x20.
>
> Not sure I understand. FISs can have different sizes depending on the payload they are. The one you are looking at here is the d2h init FIS.
>
> From the SATA 1.0a spec:
>
> FIS Type - Set to a value of 34h. Defines the rest of the FIS fields. Defines the length of the
> FIS as five Dwords.
>
> So yes, you are right. The register FIS is 20 bytes, not 0x20 bytes long.
>
> Does this fix some actual breakage for you?
In theory the SDBFIS could be overwritten with zeros. No idea what this
means or if it matters in practice.
Kevin
next prev parent reply other threads:[~2012-05-23 10:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-22 23:26 [Qemu-devel] [PATCH] ahci: SATA FIS is 20 bytes, not 0x20 Daniel Verkamp
2012-05-23 9:13 ` Kevin Wolf
2012-05-23 9:53 ` Alexander Graf
2012-05-23 10:04 ` Kevin Wolf [this message]
2012-05-23 15:48 ` Stefan Weil
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