From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=60275 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Q2NGP-0003mG-R5 for qemu-devel@nongnu.org; Wed, 23 Mar 2011 08:34:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Q2NGM-00015t-Tw for qemu-devel@nongnu.org; Wed, 23 Mar 2011 08:34:12 -0400 Received: from mail-gw0-f45.google.com ([74.125.83.45]:62975) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Q2NGM-00015l-QN for qemu-devel@nongnu.org; Wed, 23 Mar 2011 08:34:10 -0400 Received: by gwb19 with SMTP id 19so3991577gwb.4 for ; Wed, 23 Mar 2011 05:34:10 -0700 (PDT) Message-ID: <4D89E8B8.6010404@codemonkey.ws> Date: Wed, 23 Mar 2011 07:34:00 -0500 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: [PATCH 07/11] eeprom93xx: Use the new hack macro to avoid duplicate field names References: <1300839376-22520-1-git-send-email-aliguori@us.ibm.com> <1300839376-22520-8-git-send-email-aliguori@us.ibm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: quintela@redhat.com Cc: Jan Kiszka , Anthony Liguori , qemu-devel@nongnu.org On 03/23/2011 04:58 AM, Juan Quintela wrote: > Anthony Liguori wrote: >> I don't fully understand this hack business but we need field to be unique so.. >> >> Signed-off-by: Anthony Liguori >> --- >> hw/eeprom93xx.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/hw/eeprom93xx.c b/hw/eeprom93xx.c >> index cfa695d..f1d75ec 100644 >> --- a/hw/eeprom93xx.c >> +++ b/hw/eeprom93xx.c >> @@ -114,7 +114,7 @@ static const VMStateInfo vmstate_hack_uint16_from_uint8 = { >> }; >> >> #define VMSTATE_UINT16_HACK_TEST(_f, _s, _t) \ >> - VMSTATE_SINGLE_TEST(_f, _s, _t, 0, vmstate_hack_uint16_from_uint8, uint16_t) >> + VMSTATE_SINGLE_TEST_HACK(_f, _s, _t, 0, vmstate_hack_uint16_from_uint8, uint16_t) >> >> static bool is_old_eeprom_version(void *opaque, int version_id) >> { > After the fact, we need to promote it as "full types". > > Basically it is needed when we sent a field with a different size that > we use it on the struct. > > if we have > > struct FOOState { > int32_t bar; > .... > } > > and it is sent as > > VMSTATE_INT8(bar, ....) > > In this case, I went through the whole device, checed that int8_t was > enough and did the change. > > But if we have: > > struct FOOState { > int8_t bar; > .... > } > > and it is sent as > > VMSTATE_INT32(bar, ....) > > Then it is not trivial :-( > > We change FOOState to int32 or we break migration format. Here is where > the _HACK suffix appeared. > > I thought it was not going to be needed a lot, but there are several > devices that just sent everything over the wire as uint32, independently > of its type. Could we get away with just doing: VMSTATE_UNUSED(3), VMSTATE_UINT8(bar, ...), That's fully compatible on the wire and seems to be a clearer expression of exactly what the problem is. Regards, Anthony Liguori > Later, Juan. >