On Tue, 1 Jul 2025 15:26:26 +0200
Eric Auger <eric.au...@redhat.com> wrote:
> Hi Jonathan,
>
> On 6/25/25 6:19 PM, Jonathan Cameron via wrote:
> > Code based on i386/pc enablement.
> > The memory layout places space for 16 host bridge register regions after
> > the GIC_REDIST2 in the extended memmap. This is a hole in the current
> > map so adding them here has no impact on placement of other memory regions
> > (tested with enough CPUs for GIC_REDIST2 to be in use.)
>
> Doesn't it depend on the init RAM size setting.
> if the init RAM top + REDIST2 aligns to a 256MB boundary (size of the
> PCI ECAM) aren't you likely to have no hole?
Hi Eric,
Is that possible? I think the device_memory_base being force to align
to a 1 GiB means that never happens. That seems to occur even
if there is no device_memory.
device_memory_base =
ROUND_UP(vms->memmap[VIRT_MEM].base + ms->ram_size, GiB);
device_memory_size = ms->maxram_size - ms->ram_size + ms->ram_slots * GiB;
/* Base address of the high IO region */
memtop = base = device_memory_base + ROUND_UP(device_memory_size, GiB);
//So here we are GiB aligned.
...
if (base < vms->memmap[VIRT_MEM].base + LEGACY_RAMLIMIT_BYTES) {
base = vms->memmap[VIRT_MEM].base + LEGACY_RAMLIMIT_BYTES;
}
//That's 256 GiB in or leave it alone as more than that but GiB aligned.
/* We know for sure that at least the memory fits in the PA space */
vms->highest_gpa = memtop - 1;
virt_set_high_memmap(vms, base, pa_bits);
So I think I'm fine. I should call out that REDIST2 is GiB
aligned though in this patch description.
>
>
> >
> > The CFMWs are placed above the extended memmap. Note the confusing
> > existing variable highest_gpa is the highest_gpa that has been allocated
> > at a particular point in setting up the memory map.
> what kind of improvement would you foresee wrt highest_gpa?
This was mostly a response to Peter expressed that he was expecting
highest_gpa to reflect the limit, not the highest yet seen.
I'm not sure how to resolve that without having awkward naming
like highest_gpa_sofar. There are existing comments where it is updated
so I'm not thinking we need to change anything for this.
Thanks for taking a look,
Jonathan
