Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help

[Anthony Liguori]

On 07/21/2010 03:32 PM, Bruce Rogers wrote:
> Libvirt parses qemu help output to determine qemu features. In particular
>   it probes for the following: "cache=writethrough|writeback|none". The
>   addition of the unsafe cache mode was inserted within this string, as
>   opposed to being added to the end, which impacted libvirt's probe.
>   Unbreak libvirt by keeping the existing cache modes intact and add
>   unsafe to the end.
>
> This problem only manifests itself if a caching mode is explicitly
> specified in the libvirt xml, in which case older syntax for caching is
> passed to qemu, which it  no longer understands.
>
> Signed-off-by: Bruce Rogers<address@hidden>
>    

Errr, libvirt is still doing this?

This comes up frequently and it's a real PITA.  Help text is not a 
feature probing interface.  This is a libvirt bug and it needs to be 
fixed in libvirt.

Regards,

Anthony Liguori

> ---
>   qemu-options.hx |    2 +-
>   1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 0d7dd90..9ecc54e 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -118,7 +118,7 @@ ETEXI
>   DEF("drive", HAS_ARG, QEMU_OPTION_drive,
>       "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
>       "       [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n"
> -    "       [,cache=writethrough|writeback|unsafe|none][,format=f]\n"
> +    "       [,cache=writethrough|writeback|none|unsafe][,format=f]\n"
>       "       [,serial=s][,addr=A][,id=name][,aio=threads|native]\n"
>       "       [,readonly=on|off]\n"
>       "                use 'file' as a drive image\n", QEMU_ARCH_ALL)
>