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Re: [Qemu-devel] [PATCH v2] kvm: Fix enable_cap helpers on older gcc
From: |
Thomas Huth |
Subject: |
Re: [Qemu-devel] [PATCH v2] kvm: Fix enable_cap helpers on older gcc |
Date: |
Mon, 12 May 2014 11:56:49 +0200 |
On Mon, 12 May 2014 11:51:37 +0200
Alexander Graf <address@hidden> wrote:
> Commit 40f1ee27aa1 introduced handy helpers for enable_cap calls on
> vcpu and vm level. Unfortunately some older gcc versions (4.7.1, 4.6)
> seem to choke on signedness detection in inline created variables:
>
> target-ppc/kvm.c: In function 'kvmppc_booke_watchdog_enable':
> target-ppc/kvm.c:1302:21: error: comparison of unsigned expression < 0 is
> always false [-Werror=type-limits]
> target-ppc/kvm.c: In function 'kvmppc_set_papr':
> target-ppc/kvm.c:1504:21: error: comparison of unsigned expression < 0 is
> always false [-Werror=type-limits]
>
> However - thanks to Thomas Huth for the suggestion - we can just cast the
> offending potentially 0 value to a signed type, making the comparison signed.
>
> Signed-off-by: Alexander Graf <address@hidden>
>
> ---
>
> v1 -> v2:
>
> - only do cast, leaving readability intact
>
> ---
> include/sysemu/kvm.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index 192fe89..76c39cc 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -302,7 +302,7 @@ int kvm_check_extension(KVMState *s, unsigned int
> extension);
> }; \
> uint64_t args_tmp[] = { __VA_ARGS__ }; \
> int i; \
> - for (i = 0; i < ARRAY_SIZE(args_tmp) && \
> + for (i = 0; i < (int)ARRAY_SIZE(args_tmp) && \
> i < ARRAY_SIZE(cap.args); i++) { \
> cap.args[i] = args_tmp[i]; \
> } \
> @@ -317,7 +317,7 @@ int kvm_check_extension(KVMState *s, unsigned int
> extension);
> }; \
> uint64_t args_tmp[] = { __VA_ARGS__ }; \
> int i; \
> - for (i = 0; i < ARRAY_SIZE(args_tmp) && \
> + for (i = 0; i < (int)ARRAY_SIZE(args_tmp) && \
> i < ARRAY_SIZE(cap.args); i++) { \
> cap.args[i] = args_tmp[i]; \
> } \
Looks much better this way :-)
Reviewed-by: Thomas Huth <address@hidden>