Re: nanobsd [was Re: Cross compiling user applications for armv7]

On September 22, 2025 12:26:13 AM GMT+03:00, Konstantin Belousov <kostikbel@gmail.com> wrote:
>On Sun, Sep 21, 2025 at 01:01:04PM -0600, Warner Losh wrote:
>> Does FreeBSD even run on a system with less than 1GB?
>
>We boot on 256M machine on amd64.  I was not able to test smaller configsi
>due to EFI loader requiring 256M to start.
>
>I am sure that minimal kernel fits even in 64M, if allowed by loader.
>Not sure about 32M.
>

i ran amd64 qemu on amd64 host with 13, maybe 14 installer. so relatively fat kernel

i ran it lower and lower to see low can i go. and i think at 96m kernel was like nooope. maybe it was lower still

i bet it could go lower. i think those are ram sizes we don't really see anymore

the use case here would be maybe just kernel and simple program and fully offline machine. i don't have any of this, but i have good imagination

maybe *actual* 486, once you take old release and / or put 486 back into kernel

not sure what 1g would mean but 1g is relatively large even in 2025

i recall something from commit logs telling something not fitting into minimal 128g reqs

and i looks like my installer didn't boot efi so maybe this allowed less than 256m

i'm testing here, with installer, and between 14.2 and 14.3 seems like ram reqs have gone up again

14.3:

95m - still boots multiuser
94m - kernel won't boot (load fully?)
89m - loader can't load kernel at all
65m - loader won't load

panic: Could not malloc 163840 bytes with M_WAITOK from /usr/src/sys/contrib/ope
  nzfs/module/zstd/zfs_zstd.c line 788

2m - "loader loader" won't load, just spins a bar a bit
1m - same

<1m - nothing boots (really a 64bit machine with less than 1m ram?)

tests performed by:

qemu-system-x86
_64 -m x -display curses -k sv -rtc base=localtime -drive file=FreeBSD-14.3-RELEASE
-amd64-memstick-custom.img,format=raw,discard=unmap,detect-zeroes=unmap

i'm not sure of the correctness of emulation

but this should be below normal hw. tho vm's exist

but yeah i'm surprised that 1g is considered low ram nowadays... in embedded