On 04/27/2018 08:27 PM, Jan Kiszka wrote: > On 2018-04-27 11:36, Ralf Ramsauer wrote: >> On x86, we already use the communication region to pass certain platform >> specific information to guests. So let's do this on all ARM >> architectures as well. This patch is a preparation for that. >> >> Let's use guest paddr 0x80000000 (2GiB) for the comm region, which >> doesn't seem to collide with any existing (MMIO) region of our current >> inmates. > > So you really checked them all? Also validated that there is no > collision with any of the virtual mmcfg region we define (that's in the > system config then)?
I manually checked them, including the mmcfg region. But I think it's worth crosschecking them. Of course, 0x80000000 overlaps with physical RAM on most ARM platforms, but that's not an issue for the communication region in inmates. The point of this address is that on most platforms, MMIO regions are spread somewhere below 0x80000000, where it's on the one hand hard to find a common free region, and on the other it's likely to get a new board where that address might be in use. Ralf > >> >> Side note: >> Even if the communication region is not used by inmates, the hypervisor >> will always statically allocate this memory region in its struct cell. >> >> So there is no waste of memory if we expose that region to our guests. > > Then might be the need to allocate additional page table pages if that > virtual address is not covered by an existing page directory. Right, maybe better leave out that one... Ralf > > Jan > -- You received this message because you are subscribed to the Google Groups "Jailhouse" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
