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Re: [Xen-devel] [PATCH] fix xenctl_cpumap translation to handle bitops a

To: Jimi Xenidis <jimix@xxxxxxxxxxxxxx>, Keir Fraser <keir@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] fix xenctl_cpumap translation to handle bitops accessed like arrays
From: Keir Fraser <keir@xxxxxxxxxxxxx>
Date: Mon, 18 Dec 2006 17:55:59 +0000
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On 18/12/06 16:50, "Jimi Xenidis" <jimix@xxxxxxxxxxxxxx> wrote:

>> another
>> a uint64_t. Perhaps we should fix so they pass down 8-bit units (as
>> the type
>> of xenctl_cpumap_t would suggest) and then we could have
>> byte_to_long_bitmap
>> and long_to_byte_bitmap in Xen
> 
> Are you suggesting to still use bits in the bytes?
> If so, then do you want "C" ordering in the byte or arch bit ordering?
> Perhaps we simply to us the byte array as a list of CPU numbers, with
> -1 to terminate?

I mean bits 8k to 8k+7 inclusive are contained in byte at offset k in the
cpumap, and in the obvious order (8k is least significant bit; 8k+7 is most
significant). This is the byte-oriented bitmap type that your bitops.h goes
on about. Since xenctl_cpumap_t is defined as a byte array and byte count,
this interpretation would make sense.

 -- Keir


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