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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Mon, 19 Oct 2015 21:42:58 +0200
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Subject: Re: [Qemu-devel] [PATCH] xen-platform: Replace assert() with
 appropriate error reporting
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To: Eduardo Habkost <ehabkost@redhat.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: qemu-devel@nongnu.org



On 19/10/2015 20:39, Eduardo Habkost wrote:
> Commit dbb7405d8caad0814ceddd568cb49f163a847561 made it possible to
> trigger an assert using "-device xen-platform". Replace it with
> appropriate error reporting.
> 
> Before:
> 
>   $ qemu-system-x86_64 -device xen-platform
>   qemu-system-x86_64: hw/i386/xen/xen_platform.c:391: xen_platform_initfn: Assertion `xen_enabled()' failed.
>   Aborted (core dumped)
>   $
> 
> After:
> 
>   $ qemu-system-x86_64 -device xen-platform
>   qemu-system-x86_64: -device xen-platform: xen-platform device requires the Xen accelerator
>   qemu-system-x86_64: -device xen-platform: Device initialization failed
>   $
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
>  hw/i386/xen/xen_platform.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/i386/xen/xen_platform.c b/hw/i386/xen/xen_platform.c
> index 8682c42..5667f29 100644
> --- a/hw/i386/xen/xen_platform.c
> +++ b/hw/i386/xen/xen_platform.c
> @@ -33,6 +33,7 @@
>  #include "trace.h"
>  #include "exec/address-spaces.h"
>  #include "sysemu/block-backend.h"
> +#include "qemu/error-report.h"
>  
>  #include <xenguest.h>
>  
> @@ -388,7 +389,10 @@ static int xen_platform_initfn(PCIDevice *dev)
>      uint8_t *pci_conf;
>  
>      /* Device will crash on reset if xen is not initialized */
> -    assert(xen_enabled());
> +    if (!xen_enabled()) {
> +        error_report("xen-platform device requires the Xen accelerator");

You can use PCIDeviceClass's realize (see Stefano's
http://thread.gmane.org/gmane.comp.emulators.qemu/369998) to achieve
better error propagation.

Paolo

> +        return -1;
> +    }
>  
>      pci_conf = dev->config;
>  
>