* [Qemu-devel] [PATCH] i386/kvm: Fix build with -m32
@ 2019-06-24 19:02 Max Reitz
2019-06-24 19:21 ` Eduardo Habkost
0 siblings, 1 reply; 5+ messages in thread
From: Max Reitz @ 2019-06-24 19:02 UTC (permalink / raw)
To: qemu-devel
Cc: Paolo Bonzini, Richard Henderson, Marcelo Tosatti,
Eduardo Habkost, Max Reitz
find_next_bit() takes a pointer of type "const unsigned long *", but the
first argument passed here is a "uint64_t *". These types are
incompatible when compiling qemu with -m32.
Just cast it to "const void *", find_next_bit() works fine with any type
on little-endian hosts (which x86 is).
Fixes: c686193072a47032d83cb4e131dc49ae30f9e5d
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
target/i386/kvm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index e4b4f5756a..1b5f3b1c00 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -1050,7 +1050,7 @@ static int hv_cpuid_check_and_set(CPUState *cs, struct kvm_cpuid2 *cpuid,
}
deps = kvm_hyperv_properties[feature].dependencies;
- while ((dep_feat = find_next_bit(&deps, 64, dep_feat)) < 64) {
+ while ((dep_feat = find_next_bit((const void *)&deps, 64, dep_feat)) < 64) {
if (!(hyperv_feat_enabled(cpu, dep_feat))) {
fprintf(stderr,
"Hyper-V %s requires Hyper-V %s\n",
--
2.21.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [Qemu-devel] [PATCH] i386/kvm: Fix build with -m32
2019-06-24 19:02 [Qemu-devel] [PATCH] i386/kvm: Fix build with -m32 Max Reitz
@ 2019-06-24 19:21 ` Eduardo Habkost
2019-06-24 19:26 ` Max Reitz
0 siblings, 1 reply; 5+ messages in thread
From: Eduardo Habkost @ 2019-06-24 19:21 UTC (permalink / raw)
To: Max Reitz; +Cc: Paolo Bonzini, Marcelo Tosatti, qemu-devel, Richard Henderson
On Mon, Jun 24, 2019 at 09:02:14PM +0200, Max Reitz wrote:
> find_next_bit() takes a pointer of type "const unsigned long *", but the
> first argument passed here is a "uint64_t *". These types are
> incompatible when compiling qemu with -m32.
>
> Just cast it to "const void *", find_next_bit() works fine with any type
> on little-endian hosts (which x86 is).
>
> Fixes: c686193072a47032d83cb4e131dc49ae30f9e5d
> Signed-off-by: Max Reitz <mreitz@redhat.com>
Why not declare kvm_hyperv_properties.dependencies with the right
type for bitmaps, using
unsigned long dependencies[BITS_TO_LONGS(64)]
?
> ---
> target/i386/kvm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index e4b4f5756a..1b5f3b1c00 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -1050,7 +1050,7 @@ static int hv_cpuid_check_and_set(CPUState *cs, struct kvm_cpuid2 *cpuid,
> }
>
> deps = kvm_hyperv_properties[feature].dependencies;
> - while ((dep_feat = find_next_bit(&deps, 64, dep_feat)) < 64) {
> + while ((dep_feat = find_next_bit((const void *)&deps, 64, dep_feat)) < 64) {
> if (!(hyperv_feat_enabled(cpu, dep_feat))) {
> fprintf(stderr,
> "Hyper-V %s requires Hyper-V %s\n",
> --
> 2.21.0
>
--
Eduardo
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Qemu-devel] [PATCH] i386/kvm: Fix build with -m32
2019-06-24 19:21 ` Eduardo Habkost
@ 2019-06-24 19:26 ` Max Reitz
2019-06-24 19:30 ` Max Reitz
0 siblings, 1 reply; 5+ messages in thread
From: Max Reitz @ 2019-06-24 19:26 UTC (permalink / raw)
To: Eduardo Habkost
Cc: Paolo Bonzini, Marcelo Tosatti, qemu-devel, Richard Henderson
On 24.06.19 21:21, Eduardo Habkost wrote:
> On Mon, Jun 24, 2019 at 09:02:14PM +0200, Max Reitz wrote:
>> find_next_bit() takes a pointer of type "const unsigned long *", but the
>> first argument passed here is a "uint64_t *". These types are
>> incompatible when compiling qemu with -m32.
>>
>> Just cast it to "const void *", find_next_bit() works fine with any type
>> on little-endian hosts (which x86 is).
>>
>> Fixes: c686193072a47032d83cb4e131dc49ae30f9e5d
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>
> Why not declare kvm_hyperv_properties.dependencies with the right
> type for bitmaps, using
> unsigned long dependencies[BITS_TO_LONGS(64)]
> ?
How would you (statically) initialize that field, then?
I cannot imagine a reasonable static way that does not invoke the same
“The host must be little-endian, so it’s OK” assumption.
The better question is perhaps, why not use ffsll(). Hm. I don’t know,
maybe I should?
Max
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Qemu-devel] [PATCH] i386/kvm: Fix build with -m32
2019-06-24 19:26 ` Max Reitz
@ 2019-06-24 19:30 ` Max Reitz
2019-06-24 19:56 ` Eduardo Habkost
0 siblings, 1 reply; 5+ messages in thread
From: Max Reitz @ 2019-06-24 19:30 UTC (permalink / raw)
To: Eduardo Habkost
Cc: Paolo Bonzini, Marcelo Tosatti, qemu-devel, Richard Henderson
On 24.06.19 21:26, Max Reitz wrote:
> On 24.06.19 21:21, Eduardo Habkost wrote:
>> On Mon, Jun 24, 2019 at 09:02:14PM +0200, Max Reitz wrote:
>>> find_next_bit() takes a pointer of type "const unsigned long *", but the
>>> first argument passed here is a "uint64_t *". These types are
>>> incompatible when compiling qemu with -m32.
>>>
>>> Just cast it to "const void *", find_next_bit() works fine with any type
>>> on little-endian hosts (which x86 is).
>>>
>>> Fixes: c686193072a47032d83cb4e131dc49ae30f9e5d
>>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>>
>> Why not declare kvm_hyperv_properties.dependencies with the right
>> type for bitmaps, using
>> unsigned long dependencies[BITS_TO_LONGS(64)]
>> ?
>
> How would you (statically) initialize that field, then?
>
> I cannot imagine a reasonable static way that does not invoke the same
> “The host must be little-endian, so it’s OK” assumption.
Sorry, brain fart. That’s not the problem because in either case, the
lower index will receive the lower-indexed bits.
But we’d still have to deal with the fact that it could either be one or
two indices, which doesn’t seem nice to initialize either.
Max
> The better question is perhaps, why not use ffsll(). Hm. I don’t know,
> maybe I should?
>
> Max
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Qemu-devel] [PATCH] i386/kvm: Fix build with -m32
2019-06-24 19:30 ` Max Reitz
@ 2019-06-24 19:56 ` Eduardo Habkost
0 siblings, 0 replies; 5+ messages in thread
From: Eduardo Habkost @ 2019-06-24 19:56 UTC (permalink / raw)
To: Max Reitz; +Cc: Paolo Bonzini, Marcelo Tosatti, qemu-devel, Richard Henderson
On Mon, Jun 24, 2019 at 09:30:26PM +0200, Max Reitz wrote:
> On 24.06.19 21:26, Max Reitz wrote:
> > On 24.06.19 21:21, Eduardo Habkost wrote:
> >> On Mon, Jun 24, 2019 at 09:02:14PM +0200, Max Reitz wrote:
> >>> find_next_bit() takes a pointer of type "const unsigned long *", but the
> >>> first argument passed here is a "uint64_t *". These types are
> >>> incompatible when compiling qemu with -m32.
> >>>
> >>> Just cast it to "const void *", find_next_bit() works fine with any type
> >>> on little-endian hosts (which x86 is).
> >>>
> >>> Fixes: c686193072a47032d83cb4e131dc49ae30f9e5d
> >>> Signed-off-by: Max Reitz <mreitz@redhat.com>
> >>
> >> Why not declare kvm_hyperv_properties.dependencies with the right
> >> type for bitmaps, using
> >> unsigned long dependencies[BITS_TO_LONGS(64)]
> >> ?
> >
> > How would you (statically) initialize that field, then?
> >
> > I cannot imagine a reasonable static way that does not invoke the same
> > “The host must be little-endian, so it’s OK” assumption.
>
> Sorry, brain fart. That’s not the problem because in either case, the
> lower index will receive the lower-indexed bits.
>
> But we’d still have to deal with the fact that it could either be one or
> two indices, which doesn’t seem nice to initialize either.
Right, a uint64_t field is more convenient to initialize.
>
> Max
>
> > The better question is perhaps, why not use ffsll(). Hm. I don’t know,
> > maybe I should?
uint64_t + ffsll() seems simple and appropriate.
--
Eduardo
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-06-24 19:57 UTC | newest]
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2019-06-24 19:02 [Qemu-devel] [PATCH] i386/kvm: Fix build with -m32 Max Reitz
2019-06-24 19:21 ` Eduardo Habkost
2019-06-24 19:26 ` Max Reitz
2019-06-24 19:30 ` Max Reitz
2019-06-24 19:56 ` Eduardo Habkost
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