From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH v5 RFC 11/14] tools/libxc: x86 HVM save code
Date: Thu, 12 Jun 2014 18:07:02 +0100
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To: David Vrabel <david.vrabel@citrix.com>
Cc: Frediano Ziglio <frediano.ziglio@citrix.com>, Xen-devel <xen-devel@lists.xen.org>
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On 12/06/14 16:55, David Vrabel wrote:
> On 11/06/14 19:14, Andrew Cooper wrote:
>> --- /dev/null
>> +++ b/tools/libxc/saverestore/save_x86_hvm.c
> ...
>> +static int write_hvm_params(struct context *ctx)
>> +{
> ...
>> +
>> +    for ( i = 0; i < ARRAY_SIZE(params); i++ )
>> +    {
>> +        uint32_t index = params[i];
>> +        uint64_t value;
>> +
>> +        rc = xc_get_hvm_param(xch, ctx->domid, index, (unsigned long *)&value);
>> +        if ( rc )
>> +        {
>> +            /* Gross XenServer hack. Consider HVM_PARAM_CONSOLE_PFN failure
>> +             * nonfatal. This is related to the fact it is impossible to
>> +             * distinguish "no console" from a console at pfn/evtchn 0.
>> +             *
>> +             * TODO - find a compatible way to fix this.
>> +             */
>> +            if ( index == HVM_PARAM_CONSOLE_PFN )
>> +                continue;
> Um. Is this really needed with upstream Xen?
>
> David

What is needed with upstream Xen is way of representing "no console". 
The XenServer way of unconditionally failing the get_param hypercall
with -EINVAL is not suitable.

This particular hack however shouldn't have slipped in.  It comes as a
side effect of testing this series under XenServer.

~Andrew