Re: [Qemu-devel] [RFC] map 64-bit PCI devices after all possible RAM

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Oct 09, 2013 at 02:23:04PM +0200, Igor Mammedov wrote:
> I'm posting it to get an oppinion on one of possible approaches
> on where to map a hotplug memory.
> 
> This patch assumes that a space for hotplug memory is located right
> after RamSizeOver4G region and QEMU will provide romfile to specify
> where it ends so that BIOS could know from what base to start
> 64-bit PCI devices mapping.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>

Well there are two things bios does with RamSizeOver4G:
determine where to map PCI devices, and fill in smbios.

I wonder whether QEMU should fill smbios from qemu too,
that would let us side-step the issue and just make
RamSizeOver4G larger.

Let's see how the ACPI patchset fares first ...

> ---
>  src/fw/pciinit.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/src/fw/pciinit.c b/src/fw/pciinit.c
> index b29db99..62f8d4e 100644
> --- a/src/fw/pciinit.c
> +++ b/src/fw/pciinit.c
> @@ -18,6 +18,8 @@
>  #include "paravirt.h" // RamSize
>  #include "string.h" // memset
>  #include "util.h" // pci_setup
> +#include "byteorder.h" // le64_to_cpu
> +#include "romfile.h" // romfile_loadint
>  
>  #define PCI_DEVICE_MEM_MIN     0x1000
>  #define PCI_BRIDGE_IO_MIN      0x1000
> @@ -764,6 +766,8 @@ static void pci_bios_map_devices(struct pci_bus *busses)
>  {
>      if (pci_bios_init_root_regions(busses)) {
>          struct pci_region r64_mem, r64_pref;
> +        u64 base64 = le64_to_cpu(romfile_loadint("etc/mem64-end",
> +                                 0x100000000ULL + RamSizeOver4G));
>          r64_mem.list.first = NULL;
>          r64_pref.list.first = NULL;
>          pci_region_migrate_64bit_entries(&busses[0].r[PCI_REGION_TYPE_MEM],
> @@ -779,7 +783,7 @@ static void pci_bios_map_devices(struct pci_bus *busses)
>          u64 align_mem = pci_region_align(&r64_mem);
>          u64 align_pref = pci_region_align(&r64_pref);
>  
> -        r64_mem.base = ALIGN(0x100000000LL + RamSizeOver4G, align_mem);
> +        r64_mem.base = ALIGN(base64, align_mem);
>          r64_pref.base = ALIGN(r64_mem.base + sum_mem, align_pref);
>          pcimem64_start = r64_mem.base;
>          pcimem64_end = r64_pref.base + sum_pref;
> -- 
> 1.8.3.1