From: Ian Campbell <ian.campbell@citrix.com>
To: Julien Grall <julien.grall@citrix.com>, xen-devel@lists.xenproject.org
Cc: Vijaya.Kumar@caviumnetworks.com, stefano.stabellini@citrix.com,
manish.jaggi@caviumnetworks.com, vijay.kilari@gmail.com
Subject: Re: [PATCH v1 3/8] xen/arm: Support sign-extension for every read access
Date: Tue, 29 Sep 2015 14:13:41 +0100 [thread overview]
Message-ID: <1443532421.16718.65.camel@citrix.com> (raw)
In-Reply-To: <560A7265.3040307@citrix.com>
On Tue, 2015-09-29 at 12:13 +0100, Julien Grall wrote:
> > Or is it, couldn't we be updating a byte in the middle of the word?
>
> *r is a register, the byte/half-word/word... are always living in the
> lowest bit of the register.
So just to check:
ldrs* do support e.g odd offsets, but given a 32 bit MMIO region which
reads 0xAABBCCDD then when reading from offset 1 at this point *r contains
0x000000CC already (and not 0x0000C00) and sign extending the lowest byte
is therefore correct.
Right?
>
> > Probably figuring out the correct assertion is more hassle than it is
> > worth..
>
> I would rather skip it.
>
> [1] http://www.open-std.org/jtc1/sc22/WG14/www/docs/n1256.pdf
>
next prev parent reply other threads:[~2015-09-29 13:13 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-25 14:51 [PATCH v1 0/8] xen/arm: vgic: Support 32-bit access for 64-bit register Julien Grall
2015-09-25 14:51 ` [PATCH v1 1/8] xen/arm: io: remove mmio_check_t typedef Julien Grall
2015-09-25 16:33 ` Ian Campbell
2015-09-25 14:51 ` [PATCH v1 2/8] xen/arm: io: Extend write/read handler to pass the register in parameter Julien Grall
2015-09-25 16:36 ` Ian Campbell
2015-09-28 16:35 ` Julien Grall
2015-09-29 10:51 ` Ian Campbell
2015-09-29 11:00 ` Julien Grall
2015-09-29 11:09 ` Ian Campbell
2015-09-25 14:51 ` [PATCH v1 3/8] xen/arm: Support sign-extension for every read access Julien Grall
2015-09-25 16:44 ` Ian Campbell
2015-09-28 16:42 ` Julien Grall
2015-09-29 11:01 ` Ian Campbell
2015-09-29 11:07 ` Julien Grall
2015-09-28 18:22 ` Julien Grall
2015-09-29 11:03 ` Ian Campbell
2015-09-29 11:13 ` Julien Grall
2015-09-29 13:13 ` Ian Campbell [this message]
2015-09-29 13:16 ` Julien Grall
2015-09-25 14:51 ` [PATCH v1 4/8] xen/arm: vgic: ctlr stores a 32-bit hardware register so use uint32_t Julien Grall
2015-09-25 16:45 ` Ian Campbell
2015-09-25 14:51 ` [PATCH v1 5/8] xen/arm: vgic: Optimize the way to store GICD_IPRIORITYR in the rank Julien Grall
2015-09-28 10:50 ` Ian Campbell
2015-09-28 17:10 ` Julien Grall
2015-09-29 10:56 ` Ian Campbell
2015-09-28 10:52 ` Ian Campbell
2015-09-28 16:43 ` Julien Grall
2015-09-25 14:51 ` [PATCH v1 6/8] xen/arm: vgic: Optimize the way to store the target vCPU " Julien Grall
2015-09-29 13:07 ` Ian Campbell
2015-09-29 13:36 ` Julien Grall
2015-09-29 14:23 ` Ian Campbell
2015-09-30 18:11 ` Julien Grall
2015-10-01 8:30 ` Ian Campbell
2015-09-25 14:51 ` [PATCH v1 7/8] xen/arm: vgic: Introduce helpers to read/write/clear/set vGIC register Julien Grall
2015-09-29 13:23 ` Ian Campbell
2015-09-29 13:48 ` Julien Grall
2015-09-29 14:24 ` Ian Campbell
2015-10-02 9:36 ` Julien Grall
2015-09-25 14:51 ` [PATCH v1 8/8] xen/arm: vgic-v3: Support 32-bit access for 64-bit registers Julien Grall
2015-09-29 13:27 ` Ian Campbell
[not found] <1443192667-16112-1-git-send-email-julien.grall@citrix.com>
2015-09-25 14:51 ` [PATCH v1 3/8] xen/arm: Support sign-extension for every read access Julien Grall
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