Re: [SeaBIOS] [PATCH 3/4] move 64bit pci window to end of address space

[Paul Menzel]

Dear Gerd,


Thank you for the patch.

Am 21.11.22 um 11:32 schrieb Gerd Hoffmann:
> When the size of the physical address space is known (PhysBits is not
> zero) move the 64bit pci io window to the end of the address space.

It’d be great, if you elaborated, why this is an improvement.


Kind regards,

Paul


> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>   src/fw/pciinit.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
>
> diff --git a/src/fw/pciinit.c b/src/fw/pciinit.c
> index badf13d3233b..ad6def93633b 100644
> --- a/src/fw/pciinit.c
> +++ b/src/fw/pciinit.c
> @@ -1128,6 +1128,14 @@ static void pci_bios_map_devices(struct pci_bus *busses)
>           r64_mem.base = le64_to_cpu(romfile_loadint("etc/reserved-memory-end", 
> 0));
>           if (r64_mem.base < 0x100000000LL + RamSizeOver4G)
>               r64_mem.base = 0x100000000LL + RamSizeOver4G;
> +        if (PhysBits) {
> +            u64 top = 1LL << PhysBits;
> +            u64 size = (ALIGN(sum_mem, (1LL<<30)) +
> +                        ALIGN(sum_pref, (1LL<<30)));
> +            if (r64_mem.base < top - size) {
> +                r64_mem.base = top - size;
> +            }
> +        }
>           r64_mem.base = ALIGN(r64_mem.base, align_mem);
>           r64_mem.base = ALIGN(r64_mem.base, (1LL<<30));    // 1G hugepage
>           r64_pref.base = r64_mem.base + sum_mem;