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Re: [Qemu-devel] [PATCH] cpu_defs: Simplify CPUTLB padding logic
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [PATCH] cpu_defs: Simplify CPUTLB padding logic |
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Date: |
Mon, 6 Jul 2015 11:00:36 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.0.1 |
On 06/07/2015 10:58, Peter Crosthwaite wrote:
>> > Which compiler version started implementing anonymous structs?
>> >
> ISO C11 standardises it apparently. But various parts of the tree use
> them now. target-arm/cpu.h, target-i386/kvm.c,
> linux-user/syscall_defs.h and linux-headers/linux/kvm.h have liberal
> use to name a few. I have seen it used in devs from time to time for
> unionifying individual registers with an array form for SW access.
>
> This led me to consider it open season on anonymous structs and unions.
Ok, I wasn't sure about anonymous structs. We definitely use anonymous
unions a lot.
>> > Or can we just add
>> >
>> > __attribute__((__aligned__(1 << CPU_TLB_ENTRY_BITS)))
>> >
> Is that more or less standard than anonymous structs?
Not standard (though there is something in C11 too) but decades old as a
GCC extension.
Paolo