From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Ian Campbell <ian.campbell@citrix.com>
Cc: Ross Lagerwall <ross.lagerwall@citrix.com>,
Wei Liu <wei.liu2@citrix.com>,
Yang Hongyang <yanghy@cn.fujitsu.com>,
Ian Jackson <Ian.Jackson@eu.citrix.com>,
Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH 16/27] tools/libxl: Infrastructure for reading a libxl migration v2 stream
Date: Tue, 16 Jun 2015 16:46:17 +0100 [thread overview]
Message-ID: <558044C9.3000904@citrix.com> (raw)
In-Reply-To: <1434468928.13744.234.camel@citrix.com>
On 16/06/15 16:35, Ian Campbell wrote:
>
>>>> + if (dc->writefd == -1) {
>>>> + ret = ERROR_FAIL;
>>>> + LOGE(ERROR, "Unable to open '%s'", path);
>>>> + goto err;
>>>> + }
>>>> + dc->maxsz = dc->bytes_to_read = rec_hdr->length - sizeof(*emu_hdr);
>>>> + stream->expected_len = dc->used = 0;
>>> expecting 0? This differs from the pattern common everywhere else and
>>> I'm not sure why.
>> The datacopier has been overloaded so many times, it is messy to use.
>>
>> In this case, we are splicing from read fd to a write fd, rather than to
>> a local buffer.
>>
>> Therefore, when the IO is complete, we expect 0 bytes in the local
>> buffer, as all data should end up in the fd.
> I think using 2 or more data copiers to cover the different
> configurations might help? You can still reuse one for the normal record
> processing but a separate dedicated one for writing the emu to a file
> might iron out a wrinkle.
I specifically do not want to risk setting two dc's running at the same
time with the same readfd.
As all of this code is reading from a single readfd, I have specifically
avoided having multiple dc structures lying around.
>
>>> And given that why not handle this in some central place rather than in
>>> the emulator only place?
>> Experimentally, some versions of Qemu barf if they have trailing zeros
>> in save file. I think they expect to find eof() on a qemu record boundary.
> What I was suggesting was to do the padding in the core, where it would
> often be a zero nop, but would save mistakes (or duplication) if some
> other record also needs such handling in the future.
I don't see an easy way of doing that, given the current divergence in
setting the dcs up in the first place.
~Andrew
next prev parent reply other threads:[~2015-06-16 15:46 UTC|newest]
Thread overview: 107+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-15 13:44 [PATCH 00/27] Libxl migration v2 Andrew Cooper
2015-06-15 13:44 ` [PATCH 01/27] tools/libxl: Fix libxl__ev_child_inuse() check for not-yet-initialised children Andrew Cooper
2015-06-16 13:21 ` Ian Campbell
2015-06-16 13:36 ` Andrew Cooper
2015-06-16 13:47 ` Ian Jackson
2015-06-16 14:05 ` Andrew Cooper
2015-06-16 15:26 ` Ian Campbell
2015-06-16 15:24 ` Ian Campbell
2015-06-16 13:39 ` Ian Jackson
2015-06-15 13:44 ` [PATCH 02/27] tools/libxc: Always compile the compat qemu variables into xc_sr_context Andrew Cooper
2015-06-16 13:22 ` Ian Campbell
2015-06-15 13:44 ` [PATCH 03/27] tools/libxl: Stash all restore parameters in domain_create_state Andrew Cooper
2015-06-16 13:37 ` Ian Campbell
2015-06-16 14:09 ` Andrew Cooper
2015-06-18 2:32 ` Yang Hongyang
2015-06-15 13:44 ` [PATCH 04/27] tools/xl: Mandatory flag indicating the format of the migration stream Andrew Cooper
2015-06-16 13:39 ` Ian Campbell
2015-06-16 14:10 ` Andrew Cooper
2015-06-15 13:44 ` [PATCH 05/27] tools/libxl: Introduce ROUNDUP() Andrew Cooper
2015-06-16 13:39 ` Ian Campbell
2015-06-15 13:44 ` [PATCH 06/27] libxl: cancellation: Preparations for save/restore cancellation Andrew Cooper
2015-06-15 13:44 ` [PATCH 07/27] libxl: cancellation: Handle SIGTERM in save/restore helper Andrew Cooper
2015-06-15 13:44 ` [PATCH 08/27] tools/libxl: Extra APIs for the save helper Andrew Cooper
2015-06-16 13:50 ` Ian Campbell
2015-06-16 15:03 ` Andrew Cooper
2015-06-15 13:44 ` [PATCH 09/27] tools/libxl: Pass restore_fd as a parameter to libxl__xc_domain_restore() Andrew Cooper
2015-06-16 13:53 ` Ian Campbell
2015-06-15 13:44 ` [PATCH 10/27] docs: Libxl migration v2 stream specification Andrew Cooper
2015-06-16 13:58 ` Ian Campbell
2015-07-08 13:49 ` Andrew Cooper
2015-07-08 13:58 ` Ian Campbell
2015-06-15 13:44 ` [PATCH 11/27] tools/python: Libxc migration v2 infrastructure Andrew Cooper
2015-06-16 14:01 ` Ian Campbell
2015-06-15 13:44 ` [PATCH 12/27] tools/python: Libxl " Andrew Cooper
2015-06-15 13:44 ` [PATCH 13/27] tools/python: Verification utility for v2 stream spec compliance Andrew Cooper
2015-06-15 13:44 ` [PATCH 14/27] tools/python: Conversion utility for legacy migration streams Andrew Cooper
2015-06-16 14:01 ` Ian Campbell
2015-06-15 13:44 ` [PATCH 15/27] tools/libxl: Migration v2 stream format Andrew Cooper
2015-06-16 14:04 ` Ian Campbell
2015-06-15 13:44 ` [PATCH 16/27] tools/libxl: Infrastructure for reading a libxl migration v2 stream Andrew Cooper
2015-06-16 14:31 ` Ian Campbell
2015-06-16 15:01 ` Andrew Cooper
2015-06-16 15:35 ` Ian Campbell
2015-06-16 15:46 ` Andrew Cooper [this message]
2015-06-17 3:09 ` Wen Congyang
2015-06-17 10:15 ` Ian Campbell
2015-06-17 10:49 ` Wen Congyang
2015-06-17 10:55 ` Ian Campbell
2015-06-17 6:03 ` Wen Congyang
2015-06-17 9:47 ` Andrew Cooper
2015-06-17 7:57 ` Wen Congyang
2015-06-17 9:50 ` Andrew Cooper
2015-06-17 10:01 ` Wen Congyang
2015-06-17 10:48 ` Andrew Cooper
2015-06-15 13:44 ` [PATCH 17/27] tools/libxl: Support converting a legacy stream to a " Andrew Cooper
2015-06-16 14:38 ` Ian Campbell
2015-06-16 15:13 ` Andrew Cooper
2015-06-16 15:38 ` Ian Campbell
2015-06-15 13:44 ` [PATCH 18/27] tools/libxl: Convert a legacy stream if needed Andrew Cooper
2015-06-15 13:44 ` [PATCH 19/27] tools/libxc+libxl+xl: Restore v2 streams Andrew Cooper
2015-06-16 14:53 ` Ian Campbell
2015-06-16 15:23 ` Andrew Cooper
2015-06-16 15:39 ` Ian Campbell
2015-06-15 13:44 ` [PATCH 20/27] tools/libxl: Infrastructure for writing a v2 stream Andrew Cooper
2015-06-16 14:57 ` Ian Campbell
2015-06-16 15:28 ` Andrew Cooper
2015-06-17 1:31 ` Yang Hongyang
2015-06-17 9:51 ` Andrew Cooper
2015-06-17 1:39 ` Wen Congyang
2015-06-17 2:24 ` Wen Congyang
2015-06-17 7:38 ` Yang Hongyang
2015-06-17 10:14 ` Wen Congyang
2015-07-10 10:55 ` Ian Campbell
2015-07-10 11:03 ` Andrew Cooper
2015-07-10 11:05 ` Ian Campbell
2015-06-15 13:44 ` [PATCH 21/27] tools/libxc+libxl+xl: Save v2 streams Andrew Cooper
2015-06-16 14:59 ` Ian Campbell
2015-06-15 13:44 ` [PATCH 22/27] docs/libxl: [RFC] Introduce CHECKPOINT_END to support migration v2 remus streams Andrew Cooper
2015-06-16 15:00 ` Ian Campbell
2015-06-16 15:30 ` Andrew Cooper
2015-06-17 3:30 ` Wen Congyang
2015-06-15 13:44 ` [PATCH 23/27] tools/libxl: [RFC] Write checkpoint records into the stream Andrew Cooper
2015-06-16 15:03 ` Ian Campbell
2015-06-16 15:53 ` Andrew Cooper
2015-06-17 7:30 ` Ian Campbell
2015-06-17 9:55 ` Andrew Cooper
2015-06-18 3:13 ` Wen Congyang
2015-06-18 9:44 ` Andrew Cooper
2015-06-15 13:44 ` [PATCH 24/27] tools/libx{c, l}: [RFC] Introduce restore_callbacks.checkpoint() Andrew Cooper
2015-06-16 2:23 ` Yang Hongyang
2015-06-17 8:20 ` Yang Hongyang
2015-06-15 13:44 ` [PATCH 25/27] tools/libxl: [RFC] Handle checkpoint records in a libxl migration v2 stream Andrew Cooper
2015-06-17 7:28 ` Wen Congyang
2015-06-15 13:44 ` [PATCH 26/27] tools/libxc: Drop all XG_LIBXL_HVM_COMPAT code from libxc Andrew Cooper
2015-06-16 15:03 ` Ian Campbell
2015-06-15 13:44 ` [PATCH 27/27] tools/libxl: Drop all knowledge of toolstack callbacks Andrew Cooper
2015-06-16 15:04 ` Ian Campbell
2015-06-16 15:06 ` Andrew Cooper
2015-06-17 10:14 ` Ian Campbell
2015-06-17 10:43 ` Andrew Cooper
2015-06-17 10:53 ` Ian Campbell
2015-06-16 2:21 ` [PATCH 00/27] Libxl migration v2 Yang Hongyang
2015-06-17 1:55 ` Wen Congyang
2015-06-17 9:45 ` Andrew Cooper
2015-07-02 7:33 ` Yang Hongyang
2015-07-02 9:26 ` Andrew Cooper
2015-07-02 9:33 ` Yang Hongyang
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