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Re: [PATCH] xen: simplify bitmap_to_xenctl_bitmap for little endian
- To: Stefano Stabellini <sstabellini@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Thu, 20 Mar 2025 08:26:32 +0100
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- Cc: andrew.cooper3@xxxxxxxxxx, michal.orzel@xxxxxxx, julien@xxxxxxx, roger.pau@xxxxxxxxxx, bertrand.marquis@xxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Thu, 20 Mar 2025 07:26:53 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 20.03.2025 01:57, Stefano Stabellini wrote:
> On Wed, 19 Mar 2025, Jan Beulich wrote:
>> What about xenctl_bitmap_to_bitmap()?
>
> Let me see first if I managed to handle bitmap_to_xenctl_bitmap well.
Well, the code looks correct to me, but the description now has gone
stale. I also wonder whether with that extra restriction the optimization
is then actually worth it. Just one further nit:
> --- a/xen/common/bitmap.c
> +++ b/xen/common/bitmap.c
> @@ -384,21 +384,33 @@ int bitmap_to_xenctl_bitmap(struct xenctl_bitmap
> *xenctl_bitmap,
> uint8_t zero = 0;
> int err = 0;
> unsigned int xen_bytes = DIV_ROUND_UP(nbits, BITS_PER_BYTE);
> - uint8_t *bytemap = xmalloc_array(uint8_t, xen_bytes);
> -
> - if ( !bytemap )
> - return -ENOMEM;
> + bool alloc = (bitmap[nbits/8] & ((1U << (nbits % 8)) - 1)) ||
Blanks missing around / here.
Jan
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