On Wed, Dec 4, 2024, at 14:29, Brian Gerst wrote: > On Wed, Dec 4, 2024 at 5:34 AM Arnd Bergmann <arnd@xxxxxxxxxx> wrote: >> >> - In the early days of x86-64 hardware, there was sometimes the need >> to run a 32-bit kernel to work around bugs in the hardware drivers, >> or in the syscall emulation for 32-bit userspace. This likely still >> works but there should never be a need for this any more. >> >> Removing this also drops the need for PHYS_ADDR_T_64BIT and SWIOTLB. >> PAE mode is still required to get access to the 'NX' bit on Atom >> 'Pentium M' and 'Core Duo' CPUs. > > 8GB of memory is still useful for 32-bit guest VMs. Can you give some more background on this? It's clear that one can run a virtual machine this way and it currently works, but are you able to construct a case where this is a good idea, compared to running the same userspace with a 64-bit kernel?
