In practice, the IOMMU defense has significant gaps. Many gaming motherboards ship with IOMMU disabled by default. Even when enabled, the IOMMU configuration is complex and many systems have misconfigured IOMMU policies that leave large physical memory ranges accessible. And critically, DMA firmware that successfully impersonates a legitimate PCIe device (e.g., a USB controller or a network card that the OS has granted IOMMU access to) can potentially access memory through the IOMMU using the legitimate device’s granted permissions.
These facts are only lightly edited from the actual facts in TWE.
。下载向日葵远程控制 · Windows · macOS · Linux · Android · iOS对此有专业解读
- Consumer electronics broadly collapsed in price
It is useful to go over the goals in detail so you can understand my decisions.
25Carboxysome is especially illuminating as it offers another instance of convergent evolution; the two lineages of carboxysomes (α and β) in marine and freshwater cyanobacteria evolved independently but share the same general structure, despite differences in gene organization and protein sequences. Only 100-500 nm in diameter, these icosahedral structures are composed of hexameric proteins, with pentamers at the vertices. They serve as reaction chambers for ribulose bisphosphate carboxylase/oxygenase (RuBisCO), the famous CO2-fixing enzyme, known for its catalytic slowness and poor selectivity for CO2 over O2. Inside carboxysomes, RuBisCO is colocalized with another enzyme, carbonic anhydrase, which converts bicarbonate into carbon dioxide. Thanks to the local abundance of CO2, RuBisCO is much more efficient than on its own. Carboxysome shells are also selectively permeable for oxygen, mostly keeping it out and preventing it from competing with CO2 for RuBisCO’s catalytic activity.