Michael, On Fri, Feb 04, 2022 at 01:48:32AM +0000, Michael Kelley (LINUX) wrote: > From: Vitaly Chikunov <vt@xxxxxxxxxxxx> Sent: Thursday, February 3, 2022 4:58 PM > > > > GCC 11.2.1 cannot understand that value 64 is excluded from the shift > > at compile time resulting in build error[1]: > > > > drivers/hv/vmbus_drv.c:2082:29: error: shift count >= width of type [-Werror,- > > Wshift-count-overflow] > > static u64 vmbus_dma_mask = DMA_BIT_MASK(64); > > ^~~~~~~~~~~~~~~~ > > ./include/linux/dma-mapping.h:76:54: note: expanded from macro 'DMA_BIT_MASK' > > #define DMA_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1)) > > ^ ~~~ > > > > Avoid using DMA_BIT_MASK macro for that corner case. > > If we need a temporary hack to solve the build problem, I can live with > that. But I see 230 other places in kernel code where DMA_BIT_MASK(64) > is used, so I'm wondering if this particular hack is effective. We need a > more comprehensive solution that fixes the definition of > DMA_BIT_MASK() so it will work with a constant '64' as the parameter. Ah, I suddenly realised that this build was using Clang 12.0.1, not GCC 11. So my patch description is wrong! Thanks, > > Michael > > > > > Cc: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx> > > Cc: Michael Kelley <mikelley@xxxxxxxxxxxxx> > > Cc: Long Li <longli@xxxxxxxxxxxxx> > > Cc: Wei Liu <wei.liu@xxxxxxxxxx> > > Link: https://lore.kernel.org/linux-hyperv/20220203235828.hcsj6najsl7yxmxa@xxxxxxxxxxxx/ > > Signed-off-by: Vitaly Chikunov <vt@xxxxxxxxxxxx> > > --- > > drivers/hv/vmbus_drv.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c > > index 17bf55fe3169..2376ee484362 100644 > > --- a/drivers/hv/vmbus_drv.c > > +++ b/drivers/hv/vmbus_drv.c > > @@ -2079,7 +2079,7 @@ struct hv_device *vmbus_device_create(const guid_t *type, > > return child_device_obj; > > } > > > > -static u64 vmbus_dma_mask = DMA_BIT_MASK(64); > > +static u64 vmbus_dma_mask = ~0ULL; > > /* > > * vmbus_device_register - Register the child device > > */ > > -- > > 2.33.0
