From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH v3 13/23] XENVER_build_id: Provide
 ld-embedded build-ids (v10)
Date: Tue, 16 Feb 2016 20:26:27 +0000
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To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Wei Liu <wei.liu2@citrix.com>, Ian Campbell <ian.campbell@citrix.com>, jinsong.liu@alibaba-inc.com, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Ian Jackson <ian.jackson@eu.citrix.com>, xen-devel@lists.xen.org, mpohlack@amazon.de, ross.lagerwall@citrix.com, Stefano Stabellini <stefano.stabellini@citrix.com>, Jan Beulich <jbeulich@suse.com>, xen-devel@lists.xenproject.org, Daniel De Graaf <dgdegra@tycho.nsa.gov>, Keir Fraser <keir@xen.org>, sasha.levin@citrix.com
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On 16/02/16 20:22, Konrad Rzeszutek Wilk wrote:
> On Tue, Feb 16, 2016 at 08:09:13PM +0000, Andrew Cooper wrote:
>> On 12/02/16 18:05, Konrad Rzeszutek Wilk wrote:
>>
>> Building the hypervisor with buildid and making it available via
>> hypercall really should be split into two different patches, especially
>> given the complexity in each.
> OK, will do.
>
>
> .. snip..
>
>>> +/* Return value is the number of bytes written, or XEN_Exx on error.
>>> + * Calling with empty parameter returns the size of build_id. */
>>> +#define XENVER_build_id 10
>>> +struct xen_build_id {
>>> +        uint32_t        len; /* IN: size of buf[]. */
>>> +#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
>>> +        unsigned char   buf[];
>>> +#elif defined(__GNUC__)
>>> +        unsigned char   buf[1]; /* OUT: Variable length buffer with build_id. */
>>> +#endif
>>> +};
>>> +typedef struct xen_build_id xen_build_id_t;
>> I am still against trying to perpetuate this broken interface.  Variable
>> length structures are a pain for everyone to use.  How about introducing
>> a brand new hypercall with a separate length and data parameters?
> As in subop to sysctl? I am fine with that (which is what I think was
> in the first iteration of this patch had). Or it could go under the
> XSPLICE subops :-)
>
> Preferences?

A completely brand new hypercall.  Then we can deprecate the existing
xenver, including moving the relevent information such as plain version
numbers and leaving the irrelevant information (compile date, etc.).

~Andrew