Re: [Xen-devel] [PATCH] tools/xend: Only add cpuid and cpuid_check to sexpr once

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Olaf Hering writes ("[Xen-devel] [PATCH] tools/xend: Only add cpuid and 
cpuid_check to sexpr once"):
> tools/xend: Only add cpuid and cpuid_check to sexpr once
> 
> When converting a XendConfig object to sexpr, cpuid and cpuid_check
> were being emitted twice in the resulting sexpr.  The first conversion
> writes incorrect sexpr, causing parsing of the sexpr to fail when xend
> is restarted and domain sexpr files in /var/lib/xend/domains/<dom-uuid>
> are read and parsed.
> 
> This patch skips the first conversion, and uses only the custom
> cpuid{_check} conversion methods called later.  It is not pretty, but
> is the least invasive fix in this complex code.

We do intend to fix bugs in xend, but I'm worried that this change
might break something.  I don't know the code at all so forgive me if
I'm asking stupid questions, but why does the first conversion emit an
invalid sexpr ?

>              for name, typ in XENAPI_CFG_TYPES.items():
>                  if name in self and self[name] not in (None, []):
> +                    # Skip cpuid and cpuid_check.  Custom conversion
> +                    # methods for these are called below.
> +                    if name in ("cpuid", "cpuid_check"):
> +                        continue

I do agree that this looks plausible because as your comment says, the
cpuid and cpuid_check values are converted explicitly later.

Thanks,
Ian.

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