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Re: [Qemu-devel] [PATCH] xen: Fix ring.h header
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH] xen: Fix ring.h header |
Date: |
Tue, 09 Jul 2019 08:24:52 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) |
Anthony PERARD <address@hidden> writes:
> The xen_[rw]?mb() macros defined in ring.h can't be used and the fact
> that there are gated behind __XEN_INTERFACE_VERSION__ means that it
> needs to be defined somewhere. QEMU doesn't implement interfaces with
> the Xen hypervisor so defining __XEN_INTERFACE_VERSION__ is pointless.
> This leads to:
> include/hw/xen/io/ring.h:47:5: error: "__XEN_INTERFACE_VERSION__"
> is not defined, evaluates to 0 [-Werror=undef]
>
> Cleanup ring.h. The xen_*mb() macros are already defined in xenctrl.h
> which is included in xen_common.h.
>
> Reported-by: Markus Armbruster <address@hidden>
> Signed-off-by: Anthony PERARD <address@hidden>
> ---
>
> Notes:
> A similar patch have been sent to the canonical version:
> https://lists.xenproject.org/archives/html/xen-devel/2019-07/msg00370.html
That patch has an additional hunk:
@@ -33,6 +33,13 @@
* - standard integers types (uint8_t, uint16_t, etc)
* They are provided by stdint.h of the standard headers.
*
+ * Before using the different macros, you need to provide the following
+ * macros:
+ * - xen_mb() a memory barrier
+ * - xen_rmb() a read memory barrier
+ * - xen_wmb() a write memory barrier
+ * Example of those can be found in xenctrl.h.
+ *
* In addition, if you intend to use the FLEX macros, you also need to
* provide the following, before invoking the FLEX macros:
* - size_t
Suggest to include it in this patch, because (1) it's useful (I think),
and (2) it reduces differences to upstream Xen's version.
>
> include/hw/xen/interface/io/ring.h | 6 ------
> 1 file changed, 6 deletions(-)
>
> diff --git a/include/hw/xen/interface/io/ring.h
> b/include/hw/xen/interface/io/ring.h
> index 1adacf09f9..704990a2c9 100644
> --- a/include/hw/xen/interface/io/ring.h
> +++ b/include/hw/xen/interface/io/ring.h
> @@ -42,12 +42,6 @@
> * and grant_table.h from the Xen public headers.
> */
>
> -#if __XEN_INTERFACE_VERSION__ < 0x00030208
> -#define xen_mb() mb()
> -#define xen_rmb() rmb()
> -#define xen_wmb() wmb()
> -#endif
> -
> typedef unsigned int RING_IDX;
>
> /* Round a 32-bit unsigned constant down to the nearest power of two. */
Regardless of my suggestion:
Reviewed-by: Markus Armbruster <address@hidden>