Re: [PATCH v1 1/4] qemu: revert latest pSeries NVDIMM design changes

On Mon, 2020-09-14 at 23:42 -0300, Daniel Henrique Barboza wrote: > In [1], changes were made to remove the existing auto-alignment > for pSeries NVDIMM devices. That design promotes strange situations > where the NVDIMM size reported in the domain XML is different > from what QEMU is actually using. We removed the auto-alignment > and relied on standard size validation. > > However, this goes against Libvirt design philosophy of not > tampering with existing guest behavior, as pointed out by Daniel > in [2]. Since we can't know for sure whether there are guests that > are relying on the auto-alignment feature to work, the changes > made in [1] are a direct violation of this rule. > > This patch reverts [1] entirely, re-enabling auto-alignment for > pSeries NVDIMM as it was before. Changes will be made to ease > the limitations of this design without hurting existing > guests. > > This reverts the following commits: > > - commit 0ee56369c8b4f2f898b6aa1ff1f51ab033be1c02, > "qemu_domain.c: change qemuDomainMemoryDeviceAlignSize() return type". > > - commit 07de813924caf37e535855541c0c1183d9d382e2, > "qemu_domain.c: do not auto-align ppc64 NVDIMMs" > > - commit 0ccceaa57c50e5ee528f7073fa8723afd62b88b7, > "qemu_validate.c: add pSeries NVDIMM size alignment validation" > > - commit 4fa2202d884414ad34d9952e72fb39b1d93c7e14, > "qemu_domain.c: make qemuDomainGetMemorySizeAlignment() public" > > - commit 2d93cbdea9d1b8dbf36bc0ffee6cb73d83d208c7, > "Revert "formatdomain.html.in: mention pSeries NVDIMM 'align down' mechanic"" > > [1] https://www.redhat.com/archives/libvir-list/2020-July/msg02010.html > [2] https://www.redhat.com/archives/libvir-list/2020-September/msg00572.html Reverting multiple commits with a single commit is sort of unusual, but in this case it seem to make sense and I don't really have a problem with it, so unless someone shouts against this approach I think we can merge it as-is. A few tweaks to the commit message, though: * keep the order of commits consistent to the one they were merged in, which more specifically means putting 2d93cbdea9d1 at the very top of the list; * lose the commas after the various commit hashes - they break convenient double-click selection in most terminals; * indent the commit subject by two spaces for better readability.

The commit is also missing your S-o-b, and as you know that's a blocker for merging.

With the above addressed, Reviewed-by: Andrea Bolognani <abologna(a)redhat.com&gt;