Date: Sat, 29 Oct 2016 17:32:17 +0200 From: Harry Schmalzbauer <freebsd@omnilan.de> To: freebsd-stable@freebsd.org Subject: Re: Unexpected ahci-hd bytes when running in bhyve(8) Message-ID: <5814C101.90805@omnilan.de> In-Reply-To: <58124200.5080306@omnilan.de> References: <58124200.5080306@omnilan.de>
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Bezüglich Harry Schmalzbauer's Nachricht vom 27.10.2016 20:05 (localtime):
> Hello,
>
> I wanted to use a "roaming" ssd with byhve/vmm, which is the home of a
> GPT based FreeBSD setup.
> I've been using this for years with ESXi and bare-metal-hosts, and
> wanted to try out bhyve.
> Unfortunately this doesn't work the way I'm used to.
> Booting of ufs:/dev/gpt/myROOT fails with error 19, loader does only see
> a diskid/BHYVEDISK, not the GPT partitions.
>
> I guess ahci-hd isn't 1:1 mapping blocks, neither does virtio-blk, since
> it shows exactly the same result, which is a bit strange to me:
> When I boot a Live-CD in vmm with the physical SSD ahci-hd attached, the
> first 8kByte of /dev/ada0 is 0x0.
>
> The same test on the host ('dd if=/dev/ada4 count=16 | hd') shows me
> PMBR and GPT content, which I also expected to see in bhyve…
>
> What am I missing?
To verify whether my assumptions might be correct at all, I installed a
bhyve guest on a file backed ahci-hd drive (/usr/local/guest.img).
The first 448 byte of that file are exactly the same when inspected on
the host as the first 448 bytes of /dev/ada4.
Inspecting /dev/ada0 inside the guest vmm, I see again the same 448
bytes when /usr/local/guest.img was attached to ahci-hd (-s
7,ahci-hd,/usr/local/guest.img).
That was what I expected.
What I don't understand is why my expectations are true for
/usr/local/guest.img but not for /dev/ada4.
Like mentioned, while reading the first 448 bytes on the host, I get
identical results from /usr/local/guest.img and /dev/ada4, but when
attaching /dev/ada4 to ahci-hd (-s 7,ahci-hd,/dev/ada4) and inspecting
inside vmm, all I see is 0x0, while ahci-hd attached
/usr/local/guest.img shows the same pmbr as on the host!?
Do I have to exclude /dev/ada4 on the host from geom? As soon as bhyve
opens /dev/ada4, all partitions vanish from the host – probably ada4
itself gets blocked somehow?
Thanks for any hint in advance,
-harry
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