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[PATCH v5 7/7] block: check availablity for preadv/pwritev on mac

Joelle van Dyne posted 7 patches 5 years, 1 month ago
Maintainers: Richard Henderson <rth@twiddle.net>, Laurent Vivier <lvivier@redhat.com>, Markus Armbruster <armbru@redhat.com>, Thomas Huth <thuth@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, Michael Roth <mdroth@linux.vnet.ibm.com>, Max Reitz <mreitz@redhat.com>, Eric Blake <eblake@redhat.com>, Jason Wang <jasowang@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Samuel Thibault <samuel.thibault@ens-lyon.org>, Joelle van Dyne <j@getutm.app>
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[PATCH v5 7/7] block: check availablity for preadv/pwritev on mac
Posted by Joelle van Dyne 5 years, 1 month ago 
macOS 11/iOS 14 added preadv/pwritev APIs. Due to weak linking, configure
will succeed with CONFIG_PREADV even when targeting a lower OS version. We
therefore need to check at run time if we can actually use these APIs.

Signed-off-by: Joelle van Dyne <j@getutm.app>
---
 block/file-posix.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/block/file-posix.c b/block/file-posix.c
index d83219df55..a9d69746a0 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1394,12 +1394,24 @@ static bool preadv_present = true;
 static ssize_t
 qemu_preadv(int fd, const struct iovec *iov, int nr_iov, off_t offset)
 {
+#ifdef CONFIG_DARWIN /* preadv introduced in macOS 11 */
+    if (!__builtin_available(macOS 11, iOS 14, watchOS 7, tvOS 14, *)) {
+        preadv_present = false;
+        return -ENOSYS;
+    } else
+#endif
     return preadv(fd, iov, nr_iov, offset);
 }
 
 static ssize_t
 qemu_pwritev(int fd, const struct iovec *iov, int nr_iov, off_t offset)
 {
+#ifdef CONFIG_DARWIN /* pwritev introduced in macOS 11 */
+    if (!__builtin_available(macOS 11, iOS 14, watchOS 7, tvOS 14, *)) {
+        preadv_present = false;
+        return -ENOSYS;
+    } else
+#endif
     return pwritev(fd, iov, nr_iov, offset);
 }
 
-- 
2.28.0
Re: [PATCH v5 7/7] block: check availablity for preadv/pwritev on mac
Posted by Philippe Mathieu-Daudé 5 years ago 
On 11/9/20 12:24 AM, Joelle van Dyne wrote:
> macOS 11/iOS 14 added preadv/pwritev APIs. Due to weak linking, configure
> will succeed with CONFIG_PREADV even when targeting a lower OS version. We
> therefore need to check at run time if we can actually use these APIs.
> 
> Signed-off-by: Joelle van Dyne <j@getutm.app>
> ---
>  block/file-posix.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/block/file-posix.c b/block/file-posix.c
> index d83219df55..a9d69746a0 100644
> --- a/block/file-posix.c
> +++ b/block/file-posix.c
> @@ -1394,12 +1394,24 @@ static bool preadv_present = true;
>  static ssize_t
>  qemu_preadv(int fd, const struct iovec *iov, int nr_iov, off_t offset)
>  {
> +#ifdef CONFIG_DARWIN /* preadv introduced in macOS 11 */
> +    if (!__builtin_available(macOS 11, iOS 14, watchOS 7, tvOS 14, *)) {

Can we change the CONFIG_PREADV ifdef'ry to run this check once
on macOS 11?

> +        preadv_present = false;
> +        return -ENOSYS;
> +    } else
> +#endif
>      return preadv(fd, iov, nr_iov, offset);
>  }
>  
>  static ssize_t
>  qemu_pwritev(int fd, const struct iovec *iov, int nr_iov, off_t offset)
>  {
> +#ifdef CONFIG_DARWIN /* pwritev introduced in macOS 11 */
> +    if (!__builtin_available(macOS 11, iOS 14, watchOS 7, tvOS 14, *)) {
> +        preadv_present = false;
> +        return -ENOSYS;
> +    } else
> +#endif
>      return pwritev(fd, iov, nr_iov, offset);
>  }
>  
>
Re: [PATCH v5 7/7] block: check availablity for preadv/pwritev on mac
Posted by Joelle van Dyne 5 years ago 
No, because if you build on a macOS 11 host but try to run it on macOS
10.15 then it will crash.

-j

On Fri, Nov 20, 2020 at 4:32 AM Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>
> On 11/9/20 12:24 AM, Joelle van Dyne wrote:
> > macOS 11/iOS 14 added preadv/pwritev APIs. Due to weak linking, configure
> > will succeed with CONFIG_PREADV even when targeting a lower OS version. We
> > therefore need to check at run time if we can actually use these APIs.
> >
> > Signed-off-by: Joelle van Dyne <j@getutm.app>
> > ---
> >  block/file-posix.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> >
> > diff --git a/block/file-posix.c b/block/file-posix.c
> > index d83219df55..a9d69746a0 100644
> > --- a/block/file-posix.c
> > +++ b/block/file-posix.c
> > @@ -1394,12 +1394,24 @@ static bool preadv_present = true;
> >  static ssize_t
> >  qemu_preadv(int fd, const struct iovec *iov, int nr_iov, off_t offset)
> >  {
> > +#ifdef CONFIG_DARWIN /* preadv introduced in macOS 11 */
> > +    if (!__builtin_available(macOS 11, iOS 14, watchOS 7, tvOS 14, *)) {
>
> Can we change the CONFIG_PREADV ifdef'ry to run this check once
> on macOS 11?
>
> > +        preadv_present = false;
> > +        return -ENOSYS;
> > +    } else
> > +#endif
> >      return preadv(fd, iov, nr_iov, offset);
> >  }
> >
> >  static ssize_t
> >  qemu_pwritev(int fd, const struct iovec *iov, int nr_iov, off_t offset)
> >  {
> > +#ifdef CONFIG_DARWIN /* pwritev introduced in macOS 11 */
> > +    if (!__builtin_available(macOS 11, iOS 14, watchOS 7, tvOS 14, *)) {
> > +        preadv_present = false;
> > +        return -ENOSYS;
> > +    } else
> > +#endif
> >      return pwritev(fd, iov, nr_iov, offset);
> >  }
> >
> >
>
Re: [PATCH v5 7/7] block: check availablity for preadv/pwritev on mac
Posted by Philippe Mathieu-Daudé 5 years ago 
On 11/20/20 4:49 PM, Joelle van Dyne wrote:
> No, because if you build on a macOS 11 host but try to run it on macOS
> 10.15 then it will crash.

I'm not asking to move the check to configure/build time,
but to do it only once at runtime...

> 
> -j
> 
> On Fri, Nov 20, 2020 at 4:32 AM Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>>
>> On 11/9/20 12:24 AM, Joelle van Dyne wrote:
>>> macOS 11/iOS 14 added preadv/pwritev APIs. Due to weak linking, configure
>>> will succeed with CONFIG_PREADV even when targeting a lower OS version. We
>>> therefore need to check at run time if we can actually use these APIs.
>>>
>>> Signed-off-by: Joelle van Dyne <j@getutm.app>
>>> ---
>>>  block/file-posix.c | 12 ++++++++++++
>>>  1 file changed, 12 insertions(+)
>>>
>>> diff --git a/block/file-posix.c b/block/file-posix.c
>>> index d83219df55..a9d69746a0 100644
>>> --- a/block/file-posix.c
>>> +++ b/block/file-posix.c
>>> @@ -1394,12 +1394,24 @@ static bool preadv_present = true;
>>>  static ssize_t
>>>  qemu_preadv(int fd, const struct iovec *iov, int nr_iov, off_t offset)
>>>  {
>>> +#ifdef CONFIG_DARWIN /* preadv introduced in macOS 11 */
>>> +    if (!__builtin_available(macOS 11, iOS 14, watchOS 7, tvOS 14, *)) {
>>
>> Can we change the CONFIG_PREADV ifdef'ry to run this check once
>> on macOS 11?
>>
>>> +        preadv_present = false;
>>> +        return -ENOSYS;
>>> +    } else
>>> +#endif
>>>      return preadv(fd, iov, nr_iov, offset);
>>>  }
>>>
>>>  static ssize_t
>>>  qemu_pwritev(int fd, const struct iovec *iov, int nr_iov, off_t offset)
>>>  {
>>> +#ifdef CONFIG_DARWIN /* pwritev introduced in macOS 11 */
>>> +    if (!__builtin_available(macOS 11, iOS 14, watchOS 7, tvOS 14, *)) {
>>> +        preadv_present = false;
>>> +        return -ENOSYS;
>>> +    } else
>>> +#endif
>>>      return pwritev(fd, iov, nr_iov, offset);
>>>  }
>>>
>>>
>>
>
Re: [PATCH v5 7/7] block: check availablity for preadv/pwritev on mac
Posted by Joelle van Dyne 5 years ago 
How about this:

static bool preadv_present = true;
static bool preadv_checked = false;

static ssize_t
qemu_preadv(int fd, const struct iovec *iov, int nr_iov, off_t offset)
{
#ifdef CONFIG_DARWIN
    if (!preadv_checked) {
        if (__builtin_available(macOS 11, iOS 14, watchOS 7, tvOS 14, *)) {
            preadv_checked = true;
        } else {
            preadv_present = false;
            return -ENOSYS;
        }
    }
#endif
    return preadv(fd, iov, nr_iov, offset);
}

-j

On Fri, Nov 20, 2020 at 10:21 AM Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>
> On 11/20/20 4:49 PM, Joelle van Dyne wrote:
> > No, because if you build on a macOS 11 host but try to run it on macOS
> > 10.15 then it will crash.
>
> I'm not asking to move the check to configure/build time,
> but to do it only once at runtime...
>
> >
> > -j
> >
> > On Fri, Nov 20, 2020 at 4:32 AM Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
> >>
> >> On 11/9/20 12:24 AM, Joelle van Dyne wrote:
> >>> macOS 11/iOS 14 added preadv/pwritev APIs. Due to weak linking, configure
> >>> will succeed with CONFIG_PREADV even when targeting a lower OS version. We
> >>> therefore need to check at run time if we can actually use these APIs.
> >>>
> >>> Signed-off-by: Joelle van Dyne <j@getutm.app>
> >>> ---
> >>>  block/file-posix.c | 12 ++++++++++++
> >>>  1 file changed, 12 insertions(+)
> >>>
> >>> diff --git a/block/file-posix.c b/block/file-posix.c
> >>> index d83219df55..a9d69746a0 100644
> >>> --- a/block/file-posix.c
> >>> +++ b/block/file-posix.c
> >>> @@ -1394,12 +1394,24 @@ static bool preadv_present = true;
> >>>  static ssize_t
> >>>  qemu_preadv(int fd, const struct iovec *iov, int nr_iov, off_t offset)
> >>>  {
> >>> +#ifdef CONFIG_DARWIN /* preadv introduced in macOS 11 */
> >>> +    if (!__builtin_available(macOS 11, iOS 14, watchOS 7, tvOS 14, *)) {
> >>
> >> Can we change the CONFIG_PREADV ifdef'ry to run this check once
> >> on macOS 11?
> >>
> >>> +        preadv_present = false;
> >>> +        return -ENOSYS;
> >>> +    } else
> >>> +#endif
> >>>      return preadv(fd, iov, nr_iov, offset);
> >>>  }
> >>>
> >>>  static ssize_t
> >>>  qemu_pwritev(int fd, const struct iovec *iov, int nr_iov, off_t offset)
> >>>  {
> >>> +#ifdef CONFIG_DARWIN /* pwritev introduced in macOS 11 */
> >>> +    if (!__builtin_available(macOS 11, iOS 14, watchOS 7, tvOS 14, *)) {
> >>> +        preadv_present = false;
> >>> +        return -ENOSYS;
> >>> +    } else
> >>> +#endif
> >>>      return pwritev(fd, iov, nr_iov, offset);
> >>>  }
> >>>
> >>>
> >>
> >

Patchew 2.1-devel-b67e4c2

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