Re: [Xen-devel] [PATCH RFC 1/2] usbif.h: don't require PAGE_SIZE to be present

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 19/10/16 11:46, Wei Liu wrote:
> If it is present, use it; otherwise use 4096. Also provide two new
> macros to let user have control over the page size used to do
> calculation.
[...]
> index 4053c24..ac38318 100644
> --- a/xen/include/public/io/usbif.h
> +++ b/xen/include/public/io/usbif.h
> @@ -216,6 +216,16 @@ struct usbif_urb_request {
>  };
>  typedef struct usbif_urb_request usbif_urb_request_t;
>  
> +/*
> + * Reference to PAGE_SIZE was overlooked when this header file was
> + * introduced. Respect PAGE_SIZE if defined, otherwise, use 4096.
> + */
> +#ifdef PAGE_SIZE
> +#define _USB_RING_PAGE_SIZE PAGE_SIZE

#define XEN_USBIF_RING_SIZE 4096

Since PAGE_SIZE on the backend is not necessarily PAGE_SIZE in the
frontend.  This is what the size has always been so it won't break anything.

And similarly for vscsiif.

David

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