Re: [Xen-devel] [PATCH v4 3/5] xen: Put EFI machinery in place

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.05.14 at 15:39, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 16/05/14 21:41, Daniel Kiper wrote:
>> @@ -0,0 +1,374 @@
>> +/*
>> + * EFI support for Xen.
>> + *
>> + * Copyright (C) 1999 VA Linux Systems
>> + * Copyright (C) 1999 Walt Drummond <drummond@xxxxxxxxxxx>
>> + * Copyright (C) 1999-2002 Hewlett-Packard Co.
>> + *  David Mosberger-Tang <davidm@xxxxxxxxxx>
>> + *  Stephane Eranian <eranian@xxxxxxxxxx>
>> + * Copyright (C) 2005-2008 Intel Co.
>> + *  Fenghua Yu <fenghua.yu@xxxxxxxxx>
>> + *  Bibo Mao <bibo.mao@xxxxxxxxx>
>> + *  Chandramouli Narayanan <mouli@xxxxxxxxxxxxxxx>
>> + *  Huang Ying <ying.huang@xxxxxxxxx>
>> + * Copyright (C) 2011 Novell Co.
>> + *  Jan Beulich <JBeulich@xxxxxxxx>
>> + * Copyright (C) 2011-2012 Oracle Co.
>> + *  Liang Tang <liang.tang@xxxxxxxxxx>
>> + * Copyright (c) 2014 Daniel Kiper, Oracle Corporation
>> + */
>> +
>> +#include <linux/bug.h>
>> +#include <linux/efi.h>
>> +#include <linux/init.h>
>> +#include <linux/string.h>
>> +
>> +#include <xen/interface/xen.h>
>> +#include <xen/interface/platform.h>
>> +
>> +#include <asm/xen/hypercall.h>
>> +
>> +#define call (op.u.efi_runtime_call)
> 
> I think not.

??? (Read: What's wrong with putting this shortcut in place?)

>> +#define DECLARE_CALL(what) \
>> +    struct xen_platform_op op; \
>> +    op.cmd = XENPF_efi_runtime_call; \
>> +    call.function = XEN_EFI_##what; \
>> +    call.misc = 0
> 
> Macros like this which explicitly create local variable with implicit
> names are evil when reading code.
> 
> If you want to do initialisation like this, then at least do something like:
> 
> #define INIT_EFI_CALL(what) \
> { .cmd = XENPF_efi_runtime_call, \
>    .u.efi_runtime_call.function = XEN_EFI_##what, \
>    .u.efi_runtime_call.misc = 0 }
> 
> And use it as:
> 
> struct xen_platform_op op = INIT_EFI_CALL(foo);

That's minimal redundancy as a goal versus (to you, but not to me)
legibility.

Jan


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