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Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_E
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register |
Date: |
Thu, 18 Aug 2016 15:56:10 +0100 |
On 18 August 2016 at 15:46, Richard Henderson <address@hidden> wrote:
> On 08/18/2016 07:14 AM, Peter Maydell wrote:
>> While we're on the subject, can somebody explain to me why we
>> use ifuncs at all? I couldn't work out why it would be better than
>> just using a straightforward function pointer -- when I tried single
>> stepping through things the ifunc approach still seemed to indirect
>> through some table or other so it wasn't actually resolving to
>> a direct function call anyway.
> No reason, I suppose.
>
> It's particularly helpful for libraries, where we don't really want the
> overhead of the initialization when it's not used.
Ah, I see.
> But (1) we don't have many of these and (2) we really don't care *that* much
> about startup time.
>
> So a simple function pointer initialized by a constructor has the same
> effect.
That seems like it would be a worthwhile change since
(a) I think it's easier to understand than ifunc magic
(b) it means we don't unnecessarily restrict ourselves to a libc
with ifunc support (musl libc doesn't do ifuncs, for instance)
thanks
-- PMM
- [Qemu-devel] [RFC PATCH v2 0/2] Live migration optimization for Thunderx platform, vijay . kilari, 2016/08/16
- [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register, vijay . kilari, 2016/08/16
- Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register, Paolo Bonzini, 2016/08/17
- Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register, Vijay Kilari, 2016/08/18
- Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register, Paolo Bonzini, 2016/08/18
- Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register, Vijay Kilari, 2016/08/18
- Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register, Paolo Bonzini, 2016/08/18
- Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register, Richard Henderson, 2016/08/18
- Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register, Peter Maydell, 2016/08/18
- Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register, Richard Henderson, 2016/08/18
- Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register,
Peter Maydell <=
- Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register, Vijay Kilari, 2016/08/19
- Re: [Qemu-devel] [RFC PATCH v2 1/2] utils: Add helper to read arm MIDR_EL1 register, Richard Henderson, 2016/08/19
[Qemu-devel] [RFC PATCH v2 2/2] utils: Add prefetch for Thunderx platform, vijay . kilari, 2016/08/16
Re: [Qemu-devel] [RFC PATCH v2 0/2] Live migration optimization for Thunderx platform, no-reply, 2016/08/16