From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH 8/9] x86/hypercall: Merge the hypercall arg tables
Date: Wed, 3 Aug 2016 16:15:08 +0100 [thread overview]
Message-ID: <5f0f2c99-e5dd-15b4-7adf-043d0f047a0b@citrix.com> (raw)
In-Reply-To: <57A225E2020000780010253F@prv-mh.provo.novell.com>
On 03/08/16 16:12, Jan Beulich wrote:
>>>> On 18.07.16 at 11:51, <andrew.cooper3@citrix.com> wrote:
>> For the same reason as c/s 33a231e3f "x86/HVM: fold hypercall tables" and
>> (TODO - changeset) "x86/pv: Merge the pv hypercall tables", this removes the
>> risk of accidentally updating only one of the tables.
> Based on this argument perhaps hypercall and args tables should
> get folded too, but I guess that's a work item for another day.
That is rather harder to do. I thought about it, but couldn't find a
neat way of doing it.
The call table is an array of pointers, while the args table is an array
of bytes. Merging them would result in excessive padding for alignment
purposes, unless it was packed, at which point we are calling
non-aligned function pointers, and taking that associated performance hit.
~Andrew
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next prev parent reply other threads:[~2016-08-03 15:15 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-18 9:51 [PATCH 0/9] x86: Move the pv hypercall into C Andrew Cooper
2016-07-18 9:51 ` [PATCH 1/9] x86/hypercall: Move some of the hvm hypercall infrastructure into hypercall.h Andrew Cooper
2016-08-02 12:50 ` Jan Beulich
2016-08-02 13:14 ` Andrew Cooper
2016-08-02 13:28 ` Jan Beulich
2016-08-02 14:04 ` Julien Grall
2016-08-02 14:17 ` Jan Beulich
2016-08-02 14:26 ` Julien Grall
2016-08-02 14:54 ` Jan Beulich
2016-08-02 14:59 ` Andrew Cooper
2016-08-02 15:05 ` Jan Beulich
2016-08-02 18:43 ` Stefano Stabellini
2016-08-03 8:53 ` Jan Beulich
2016-08-03 10:55 ` Julien Grall
2016-08-03 18:20 ` Stefano Stabellini
2016-08-04 11:27 ` Julien Grall
2016-07-18 9:51 ` [PATCH 2/9] x86/pv: Support do_set_segment_base() for compat guests Andrew Cooper
2016-08-02 12:52 ` Jan Beulich
2016-08-02 13:25 ` Andrew Cooper
2016-08-02 13:31 ` Jan Beulich
2016-08-02 13:39 ` Andrew Cooper
2016-08-02 13:47 ` Jan Beulich
2016-07-18 9:51 ` [PATCH 3/9] x86/hypercall: Move the hypercall arg tables into C Andrew Cooper
2016-08-02 12:59 ` Jan Beulich
2016-07-18 9:51 ` [PATCH 4/9] x86/pv: Implement pv_hypercall() in C Andrew Cooper
2016-08-02 13:12 ` Jan Beulich
2016-08-02 14:06 ` Andrew Cooper
2016-08-02 14:19 ` Jan Beulich
2016-08-11 11:57 ` Andrew Cooper
2016-08-11 12:20 ` Jan Beulich
2016-07-18 9:51 ` [PATCH 5/9] x86/hypercall: Move the hypercall tables into C Andrew Cooper
2016-08-02 13:23 ` Jan Beulich
2016-08-02 13:30 ` Andrew Cooper
2016-08-02 13:40 ` Jan Beulich
2016-08-11 12:00 ` Andrew Cooper
2016-07-18 9:51 ` [PATCH 6/9] xen/multicall: Rework arch multicall handling Andrew Cooper
2016-07-20 12:35 ` Julien Grall
2016-08-03 15:02 ` Jan Beulich
2016-08-03 15:12 ` Andrew Cooper
2016-07-18 9:51 ` [PATCH 7/9] x86/pv: Merge the pv hypercall tables Andrew Cooper
2016-08-03 15:07 ` Jan Beulich
2016-08-11 12:36 ` Andrew Cooper
2016-07-18 9:51 ` [PATCH 8/9] x86/hypercall: Merge the hypercall arg tables Andrew Cooper
2016-08-03 15:12 ` Jan Beulich
2016-08-03 15:15 ` Andrew Cooper [this message]
2016-08-03 15:28 ` Jan Beulich
2016-07-18 9:51 ` [PATCH 9/9] x86/hypercall: Reduce the size of the hypercall tables Andrew Cooper
2016-08-03 15:17 ` Jan Beulich
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