Re: [PATCH v2] hw/block: nvme: Fix a build error in nvme_get_feature()

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Feb 10, 2021 at 11:22:19AM +0000, Daniel P. Berrangé wrote:
> On Wed, Feb 10, 2021 at 12:15:45PM +0100, Philippe Mathieu-Daudé wrote:
> > On 2/10/21 12:12 PM, Philippe Mathieu-Daudé wrote:
> > > Hi Bin,
> > > 
> > > On 2/10/21 11:23 AM, Bin Meng wrote:
> > >> From: Bin Meng <bin.meng@windriver.com>
> > >>
> > >> Current QEMU HEAD nvme.c does not compile:
> > >>
> > >>   hw/block/nvme.c:3242:9: error: ‘result’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> > >>          trace_pci_nvme_getfeat_vwcache(result ? "enabled" : "disabled");
> > >>          ^
> > >>   hw/block/nvme.c:3150:14: note: ‘result’ was declared here
> > >>      uint32_t result;
> > >>               ^
> > > 
> > > Why isn't this catched by our CI? What is your host OS? Fedora 33?
> > 
> > Just noticed v1 and Peter's explanation:
> > https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg03528.html
> > 
> > Can you amend "default GCC 5.4 on a Ubuntu 16.04 host" information
> > please?
> 
> Well Ubuntu 16.04 hasn't been considered a supported build target for
> QEMU for a year now.
> 
> https://qemu.readthedocs.io/en/latest/system/build-platforms.html#linux-os-macos-freebsd-netbsd-openbsd
> 
>   "The project aims to support the most recent major version 
>    at all times. Support for the previous major version will 
>    be dropped 2 years after the new major version is released
>    or when the vendor itself drops support, whichever comes 
>    first."
> 
> IOW, we only aim for QEMU to be buildable on Ubuntu LTS 20.04 and 18.04
> at this point in time.  16.04 is explicitly dropped and we will increasingly
> introduce incompatibilities with it.
> 
> While this specific patch is simple, trying to keep QEMU git master
> working on 16.04 is not a goal, so I'd really suggest upgrading to
> a newer Ubuntu version at the soonest opportunity.

In particular after 6.0 QEMU is released, we'll be dropping RHEL-7
and then likely setting the  min required GCC to somewhere around
6.3 which will cut off Ubuntu 16.04 upfront.

Regards,
Daniel
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