Date: Mon, 11 Nov 2019 11:47:11 -0800 From: Mark Millard <marklmi@yahoo.com> To: bob prohaska <fbsd@www.zefox.net> Cc: freebsd-arm@freebsd.org Subject: Re: What is an invalid ASID ? Message-ID: <7D522F39-7CCB-4678-BE12-506CE8122AC2@yahoo.com> In-Reply-To: <20191111160303.GA61731@www.zefox.net> References: <20191111160303.GA61731@www.zefox.net>
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On 2019-Nov-11, at 08:03, bob prohaska <fbsd at www.zefox.net> wrote:
> While building world on a Pi3 running -current at r354546 the machine
> reported=20
> panic: invalid ASID
>=20
> For now he machine has restarted and resumed buildworld.
>=20
> Is there a glossary somewhere that offers a description of ASID?
Looks like it is arm terminology instead of FreeBSD-specific =
terminology,
though FreeBSD would have its specific style of use of such. Quoting =
from
a document about armv8:
QUOTE
Each TLB entry typically contains not only physical and virtual =
addresses, but also attributes such as memory type, cache policies, =
access permissions, the Address Space ID (ASID), and the Virtual Machine =
ID (VMID).
END QUOTE
=46rom what I see there is FreeBSD code around like:
* A pmap's cookie encodes an ASID and epoch number. Cookies for =
reserved
* ASIDs have a negative epoch number, specifically, INT_MIN. Cookies =
for
* dynamically allocated ASIDs have a non-negative epoch number.
*
* An invalid ASID is represented by -1.
. . .
#define ASID_TO_OPERAND(asid) ({ =
\
KASSERT((asid) !=3D -1, ("invalid ASID")); =
\
(uint64_t)(asid) << ASID_TO_OPERAND_SHIFT; =
\
})
It looks like a backtrace from such a panic might be of interest to the
folks dealing with such areas.
=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
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