> On Tue, Jun 23, 2020 at 06:27:51PM +0200, Christoph Hellwig wrote: > > On Tue, Jun 23, 2020 at 09:24:33PM +0800, Baolin Wang wrote: > > > Introduce a new capability macro to indicate if the controller > > > supports the memory buffer or not, instead of reading the > > > NVME_REG_CMBSZ register. > > > > This is a complex issue. The CMBS bit was only added in NVMe 1.4 as > > a backwards incompatible change, as the CMB addressing scheme can lead > > Ah, right, I think I should add another version condition: > if ((ctrl->vs >= NVME_VS(1, 4, 0) && !NVME_CAP_CMBS(dev->ctrl.cap)) || > dev->cmb_size) > return;
After more thinking, now we should read NVME_REG_VS register to get the controller version when using the CMBS bit in Capabilities register, there is no benefit, so I'll drop this patch. Thanks. > > to data corruption. The CMBS was added as part of the horribe hack > > that also involves the CBA field, which we'll need to see before > > using it to work around the addressing issue. At the same time we > > should also continue supporting the legacy pre-1.4 CMB with a warning > > (and may reject it if we know we run in a VM).
