From: Bin Meng <bin.meng@windriver.com>

Current QEMU HEAD nvme.c does not compile:

  hw/block/nvme.c: In function ‘nvme_process_sq’:
  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;
              ^

Explicitly initialize the result to fix it.

Fixes: aa5e55e3b07e ("hw/block/nvme: open code for volatile write cache")
Signed-off-by: Bin Meng <bin.meng@windriver.com>
---

 hw/block/nvme.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 5ce21b7..c122ac0 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -3228,6 +3228,7 @@ static uint16_t nvme_get_feature(NvmeCtrl *n, NvmeRequest *req)
         result = ns->features.err_rec;
         goto out;
     case NVME_VOLATILE_WRITE_CACHE:
+        result = 0;
         for (i = 1; i <= n->num_namespaces; i++) {
             ns = nvme_ns(n, i);
             if (!ns) {
-- 
2.7.4

On Wed, Feb 10, 2021 at 5:54 PM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> From: Bin Meng <bin.meng@windriver.com>
>
> Current QEMU HEAD nvme.c does not compile:
>
>   hw/block/nvme.c: In function ‘nvme_process_sq’:

Not sure why compiler reports this error happens in nvme_process_sq()?

But it should be in nvme_get_feature(). I will update the commit message in v2.

>   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;
>               ^
>
> Explicitly initialize the result to fix it.
>
> Fixes: aa5e55e3b07e ("hw/block/nvme: open code for volatile write cache")
> Signed-off-by: Bin Meng <bin.meng@windriver.com>
> ---
>
>  hw/block/nvme.c | 1 +
>  1 file changed, 1 insertion(+)
>

Regards,
Bin

On Feb 10 18:15, Bin Meng wrote:
> On Wed, Feb 10, 2021 at 5:54 PM Bin Meng <bmeng.cn@gmail.com> wrote:
> >
> > From: Bin Meng <bin.meng@windriver.com>
> >
> > Current QEMU HEAD nvme.c does not compile:
> >
> >   hw/block/nvme.c: In function ‘nvme_process_sq’:
> 
> Not sure why compiler reports this error happens in nvme_process_sq()?
> 

Yeah that is kinda wierd. Also, this went through the full CI suite.
What compiler is this?

> But it should be in nvme_get_feature(). I will update the commit message in v2.
> 
> >   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;
> >               ^
> >
> > Explicitly initialize the result to fix it.
> >
> > Fixes: aa5e55e3b07e ("hw/block/nvme: open code for volatile write cache")
> > Signed-off-by: Bin Meng <bin.meng@windriver.com>
> > ---
> >
> >  hw/block/nvme.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> 
> Regards,
> Bin
> 

On Wed, Feb 10, 2021 at 6:23 PM Klaus Jensen <its@irrelevant.dk> wrote:
>
> On Feb 10 18:15, Bin Meng wrote:
> > On Wed, Feb 10, 2021 at 5:54 PM Bin Meng <bmeng.cn@gmail.com> wrote:
> > >
> > > From: Bin Meng <bin.meng@windriver.com>
> > >
> > > Current QEMU HEAD nvme.c does not compile:
> > >
> > >   hw/block/nvme.c: In function ‘nvme_process_sq’:
> >
> > Not sure why compiler reports this error happens in nvme_process_sq()?
> >
>
> Yeah that is kinda wierd. Also, this went through the full CI suite.
> What compiler is this?
>

Yes it's quite strange.

I am using the default GCC 5.4 on a Ubuntu 16.04 host.

Regards,
Bin