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Date: Tue, 5 Dec 2017 12:44:40 +0000
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Message-ID: <20171205124439.GB2405@work-vm>
References: <20171205122740.15005-1-lvivier@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] migration: fix analyze-migration.py script
 with radix table
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To: Laurent Vivier <lvivier@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-ppc@nongnu.org, David Gibson <david@gibson.dropbear.id.au>, Bharata B Rao <bharata@linux.vnet.ibm.com>, Juan Quintela <quintela@redhat.com>, Greg Kurz <groug@kaod.org>

* Laurent Vivier (lvivier@redhat.com) wrote:
> Since commit 3a38429748 ("Add a "no HPT" encoding to HTAB migration stream")
> the HTAB migration stream contains a header set to "-1", meaning there
> is no HPT. Teach analyze-migration.py to ignore the section in this case.
> 
> Without this fix, the script fails with a dump from a POWER9 guest:
> 
> Traceback (most recent call last):
>   File "./qemu/scripts/analyze-migration.py", line 602, in <module>
>     dump.read(dump_memory = args.memory)
>   File "./qemu/scripts/analyze-migration.py", line 539, in read
>     section.read()
>   File "./qemu/scripts/analyze-migration.py", line 250, in read
>     self.file.readvar(n_valid * self.HASH_PTE_SIZE_64)
>   File "./qemu/scripts/analyze-migration.py", line 64, in readvar
>     raise Exception("Unexpected end of %s at 0x%x" % (self.filename, self.file.tell()))
> Exception: Unexpected end of migrate.dump at 0x1d4763ba
> 
> Fixes: 3a38429748 ("Add a "no HPT" encoding to HTAB migration stream")
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  scripts/analyze-migration.py | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/scripts/analyze-migration.py b/scripts/analyze-migration.py
> index 14553876a2..88ff4adb30 100755
> --- a/scripts/analyze-migration.py
> +++ b/scripts/analyze-migration.py
> @@ -234,6 +234,10 @@ class HTABSection(object):
>  
>          header = self.file.read32()
>  
> +        if (header == -1):
> +            # "no HPT" encoding
> +            return
> +
>          if (header > 0):
>              # First section, just the hash shift
>              return
> -- 
> 2.14.3
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK