Re: [PATCH 00/12] add per-domain and per-cpupool generic parameters

From: Juergen Gross <jgross@suse.com>
To: Wei Liu <wei.liu2@citrix.com>, Dario Faggioli <dfaggioli@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Tim Deegan <tim@xen.org>,
	George Dunlap <george.dunlap@citrix.com>,
	Julien Grall <julien.grall@arm.com>,
	Jan Beulich <JBeulich@suse.com>,
	xen-devel <xen-devel@lists.xenproject.org>,
	Daniel de Graaf <dgdegra@tycho.nsa.gov>,
	Ian Jackson <Ian.Jackson@eu.citrix.com>
Subject: Re: [PATCH 00/12] add per-domain and per-cpupool generic parameters
Date: Wed, 3 Oct 2018 13:07:30 +0200	[thread overview]
Message-ID: <96f4400d-ef14-5176-2c68-5527c72cfb71@suse.com> (raw)
In-Reply-To: <20181003110035.pcz7oyb66wc4cmfo@zion.uk.xensource.com>

On 03/10/2018 13:00, Wei Liu wrote:
> On Wed, Sep 26, 2018 at 07:30:38PM +0200, Dario Faggioli wrote:
>> On Fri, 2018-09-21 at 09:52 +0100, Wei Liu wrote:
>>> On Fri, Sep 21, 2018 at 07:23:23AM +0200, Juergen Gross wrote:
>>>> On 20/09/18 18:06, Wei Liu wrote:
>>>>>
>>>>> It appears that the implementation in patch 10 concatenates the
>>>>> new
>>>>> settings to the old ones. It is not very nice imo.
>>>>>
>>>>> If for the life time of the domain you set X times the same
>>>>> parameter
>>>>> you get a string of foo=bar1 foo=bar2 in the saved config file.
>>>>>
>>>>> There is probably a simple solution: make the parameter list in
>>>>> IDL a
>>>>> key value list. You then update the list accordingly.
>>>>
>>>> The problem with that approach are parameters with sub-parameters:
>>>>
>>>> par=sub1=no,sub2=yes
>>>> par=sub2=yes
>>>
>>> There is another way to solve this: further parse the sub-parameters.
>>> This doesn't require any parameter specific knowledge and there are
>>> already functions to split strings.
>>>
>> I'm not sure whether we're saying the same thing or not, but can't we,
>> when parameter 'foo', which has been set to 'bar1' already, is being
>> set to 'bar2', search d_config.b_info.parameters for the substring
>> containing 'foo=bar1', replace it with 'foo=bar2', and save d_config
>> again?
> 
> This can do, too. It is still parsing so the amount of work needed is
> more or less the same to me.

No, this isn't always correct. Think of console=tty0 console=hvc0 in
the linux kernel. You don't want hvc0 to replace tty0, but to have
both.

Juergen

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