On Sun, Jul 10, 2022 at 5:33 PM Kent Mcleod <kent.mcleo...@gmail.com> wrote:
> > >> > > > >> > I'm trying to figure out the physical memory used by the kernel. > This is > > >> > for riscv if it matters. > > >> > > Starting from the ram region defined by the device tree, I recall the > following happens for RISC-V: > - Some memory is subtracted from the start for the SBI program which I > think is 2MiB for both RV32 and RV64. This might be where most of your > memory is being lost to. There's an unmerged PR for making this value > configurable in the platform device tree: > https://github.com/seL4/seL4/pull/759 Aha, thank you (that's very hidden)! I do see the 2MB reserve in the generated DTS (gen_headers/plat/machine/devices_gen.h). And we don't have/use SBI. Any reason why this PR has yet to be merged? > - memory used by the kernel is for code + data and should be just what > is reported by the ELF segment headers. > - During boot the kernel does allocate memory dynamically but this > should be only for the rootserver and should entirely happen in the > function create_rootserver_objects() > - The remaining memory is handed to the rootserver as untypeds. The > kernel also frees code and data that was only required during startup > and releases that as untypeds too. These untypeds can be inspected in > the boot info. > > What I've done in the past is to print out the untyped list and then > audited how it corresponds to the memory usage rules listed above. > > > > > > > > I don't suppose there's some kernel variable I can print that will help > > > answer my q? > > > > > The untypeds handled to user level is the kernel's record of memory > available for allocation. During boot time, > calculate_rootserver_size() can be called to return the amount of > memory the kernel dynamically allocates for the root_server, and > during boot the range of memory used is kept in the global: region_t > rootserver_mem, but would be freed once the kernel jumps to user > level. The kernel should already print the ranges of memory it is > given to use at the start of boot.\ > Kent. > _______________________________________________ Devel mailing list -- devel@sel4.systems To unsubscribe send an email to devel-leave@sel4.systems
