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From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Joe Damato <ice799@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>,
	linux-x86_64@vger.kernel.org, linux-newbie@vger.kernel.org,
	kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vegard Nossum <vegard.nossum@gmail.com>
Subject: Re: [PATCH 00/12] x86: Cleanup idt, gdt/ldt/tss structs
Date: Tue, 28 Oct 2008 10:02:25 +1100	[thread overview]
Message-ID: <49064881.9040207@goop.org> (raw)
In-Reply-To: <49062F87.4060307@gmail.com>

Joe Damato wrote:
>> Small detail, the syntactic form you chose:
>>
>> +       if (!cpu->arch.idt[num].p)
>>
>> is not very readable because it's not obvious at first sight that 
>> ".p" intends to mean "present bit". If then idt[num].present would 
>> have been the better choice - but it's even better to not do 
>> bitfields at all but an idt_present(desc *) helper inline function.
>>
>>   
>
> OK, I'll try to use more descriptive names. As hpa pointed out in his 
> email, 'p' is the name of the field in the intel x86 documentation. 
> That's why I chose that, but I agree it isn't particularly clear.

Using bitfields would be a lot more appealing if the x86 design weren't 
so batshit insane.  Given that the addresses and limits are split of 
multiple bitfields, you need to have a set of accessors for those at 
least.  If you're going to do that, it might be worth having them for 
all the fields, at least for consistency.  Perhaps this would be too 
ugly and clumsy, but there isn't much code which really does anything 
with descriptors in detail.

    J
>
> Thanks again for the feedback,
> Joe


      reply	other threads:[~2008-10-27 23:03 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-25  3:15 [PATCH 00/12] x86: Cleanup idt, gdt/ldt/tss structs Joe Damato
2008-10-25  3:15 ` [PATCH 01/12] x86: Cleanup x86 descriptors, remove a/b fields from structs Joe Damato
2008-10-25  3:15   ` [PATCH 02/12] x86: Use new gate_struct for gate_desc Joe Damato
2008-10-29 12:53     ` Jeremy Fitzhardinge
2008-10-25  3:15   ` [PATCH 03/12] x86: Cleanup usage of struct desc_struct Joe Damato
2008-10-29 12:52     ` Jeremy Fitzhardinge
2008-10-25  3:15   ` [PATCH 04/12] x86: Add macros for gate_desc Joe Damato
2008-10-29 12:54     ` Jeremy Fitzhardinge
2008-10-25  3:15   ` [PATCH 05/12] x86: Refactor pack_gate " Joe Damato
2008-10-25  3:15   ` [PATCH 06/12] x86: Refactor pack_descriptor Joe Damato
2008-10-25  3:15   ` [PATCH 07/12] x86: Add a static initializer for IDTs Joe Damato
2008-10-25  3:15   ` [PATCH 08/12] x86: Use static intializer for IDT entries Joe Damato
2008-10-25  3:15   ` [PATCH 09/12] x86: Add static initiazlier for descriptors Joe Damato
2008-10-29 12:58     ` Jeremy Fitzhardinge
2008-10-25  3:15   ` [PATCH 10/12] x86: Use static initializers " Joe Damato
2008-10-25  3:15   ` [PATCH 11/12] x86: Use macros for getting/setting descriptors Joe Damato
2008-10-25  3:15   ` [PATCH 12/12] x86: Use struct fields instead of bitmasks Joe Damato
2008-10-29 12:56     ` Jeremy Fitzhardinge
2008-10-25  5:40 ` [PATCH 00/12] x86: Cleanup idt, gdt/ldt/tss structs Willy Tarreau
2008-10-27 10:57   ` Ingo Molnar
2008-10-25  9:39 ` walter harms
2008-10-27 10:55 ` Ingo Molnar
2008-10-27 14:34   ` H. Peter Anvin
2008-10-27 21:15   ` Joe Damato
2008-10-27 23:02     ` Jeremy Fitzhardinge [this message]

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