Install DragonFlyBSD on 48 MB RAM

[Antonio Huete Jimenez]

On 02/03/2012 2:45, Matthew Dillon wrote:
> :One of our developers tested with snapshots; it looks like the DMA
> :reserve commit is the one that made DF no longer run w/ 48MB. That
> :makes sense, as 16MB of physical memory is locked up by that commit.
> :You should be able to boot with a loader variable set to reserve less
> :physical memory.
> :
> :We someday need a better physmem allocator; the 16MB reserve is a good
> :step, but a low-fragmentation allocator would be better.
> :
> :-- vs;
>
>     It should be reserving less space on low-memory machines.
>
>          if (vm_dma_reserved == 0) {
>                  vm_dma_reserved = 16 * 1024 * 1024;     /* 16MB */
>                  if (vm_dma_reserved>  total / 16)
>                          vm_dma_reserved = total / 16;
>          }
>
>     We could try zeroing it.  Or perhaps the calculation is wrong...
>     maybe it should be basing the test on 'npages' instead of 'total'.
>     e.g. ((vm_paddr_t)npages * PAGE_SIZE / 16) instead of (total / 16).
>
>     However, we really don't support machines with so little memory,
>     even if the thing manages to boot.  If a simple change makes it work
>     then fine, but otherwise I'm skeptical of the value.
>
>     This variable is a tunable.  Try setting 'vm.dma_reserved=0' in the
>     boot loader.
>
> 					-Matt
> 					Matthew Dillon
> 					<dillon at backplane.com>
I already tried with 'vm.dma_reserved=0' set in the loader prompt and it 
doesn't boot either. What I would recommend would be to install DFly on 
the 48MB's harddisk in another machine or using VMware, during 
installation configure something like 256MB swap for example. It should 
work fine.