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Re: [Qemu-devel] [RFC PATCH v5 4/6] module: implement module loading fun
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [RFC PATCH v5 4/6] module: implement module loading function |
Date: |
Wed, 11 Sep 2013 08:06:20 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130805 Thunderbird/17.0.8 |
On 09/11/2013 07:10 AM, Alex Bligh wrote:
>
>
> --On 11 September 2013 13:38:27 +0800 Fam Zheng <address@hidden> wrote:
>
>> + switch (type) {
>> + case MODULE_LOAD_BLOCK:
>> + path = CONFIG_PREFIX "/qemu/block/";
>> + break;
>> + case MODULE_LOAD_UI:
>> + path = CONFIG_PREFIX "/qemu/ui/";
>> + break;
>> + case MODULE_LOAD_NET:
>> + path = CONFIG_PREFIX "/qemu/net/";
>> + break;
>> + default:
>> + return;
>> + }
>> +
>
> I appreciate I am coming in late into this discussion, and am only scanning
> the code quickly, so apologies if I have the wrong end of the stick.
>
> This APPEARS to load modules from
> a) a fixed path determined at compile time
> b) a path which is not dependent on qemu version
>
> This would make it hard to have 2 versions of qemu installed on a
> system at once, or even develop one version of qemu with another
> version installed. I suspect this will be hard not only for developers,
> but also for distributions, particularly if the idea is to keep vms
> running during upgrades. Consider the case where packages A and B
> both depend on qemu module package C, then you wish to upgrade to
> A', B' and C'. At some point you are likely to want both C and C'
> installed. Is the idea here that QEMU is always built with CONFIG_PREFIX
> having versioning inside it (in a distro environment)?
>
> Can I suggest that at the very least, it should be possible to specify
> an alternate path to the module directory via the CLI?
>
If we want dependencies between modules, we may well need to get the
dynamic linker involved with the search directory. This would rule
out any command-line, or monitor-line altering of the path.
But it does suggest the default being DT_RUNPATH, overridable "near"
the command-line via LD_RUN_PATH.
I also wonder about the utility of the subdirectories above, as
opposed to filename prefixes.
r~
[Qemu-devel] [RFC PATCH v5 5/6] configure: introduce --enable-modules, Fam Zheng, 2013/09/11