Commit 5ec7d098 authored by Gerd Hoffmann's avatar Gerd Hoffmann Committed by Michael S. Tsirkin
Browse files

xen: fix ram init regression 



Commit "8156d480 pc: allow raising low memory via max-ram-below-4g
option" causes a regression on xen, because it uses a different
memory split.

This patch initializes max-ram-below-4g to zero and leaves the
initialization to the memory initialization functions.  That way
they can pick different default values (max-ram-below-4g is zero
still) or use the user supplied value (max-ram-below-4g is non-zero).

Also skip the whole ram split calculation on Xen.  xen_ram_init()
does its own split calculation anyway so it is superfluous, also
this way xen_ram_init can actually see whenever max-ram-below-4g
is zero or not.

Reported-by: default avatarAnthony PERARD <anthony.perard@citrix.com>
Tested-by: default avatarAnthony PERARD <anthony.perard@citrix.com>
Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent e2c8f9e4

hw/i386/pc.c

+1 −1
Original line number Diff line number Diff line
@@ -1919,7 +1919,7 @@ static void pc_machine_initfn(Object *obj) 
                        pc_machine_get_hotplug_memory_region_size,

                        NULL, NULL, NULL, &error_abort);



    pcms->max_ram_below_4g = 0xe0000000; /* 3.5G */

    pcms->max_ram_below_4g = 0; /* use default */

    object_property_add(obj, PC_MACHINE_MAX_RAM_BELOW_4G, "size",

                        pc_machine_get_max_ram_below_4g,

                        pc_machine_set_max_ram_below_4g,

hw/i386/pc_piix.c

+28 −22
Original line number Diff line number Diff line
@@ -108,12 +108,21 @@ static void pc_init1(MachineState *machine, 
     *    so legacy non-PAE guests can get as much memory as possible in

     *    the 32bit address space below 4G.

     *

     *  - Note that Xen has its own ram setp code in xen_ram_init(),

     *    called via xen_hvm_init().

     *

     * Examples:

     *    qemu -M pc-1.7 -m 4G    (old default)    -> 3584M low,  512M high

     *    qemu -M pc -m 4G        (new default)    -> 3072M low, 1024M high

     *    qemu -M pc,max-ram-below-4g=2G -m 4G     -> 2048M low, 2048M high

     *    qemu -M pc,max-ram-below-4g=4G -m 3968M  -> 3968M low (=4G-128M)

     */

    if (xen_enabled()) {

        xen_hvm_init(pcms, &ram_memory);

    } else {

        if (!pcms->max_ram_below_4g) {

            pcms->max_ram_below_4g = 0xe0000000; /* default: 3.5G */

        }

        lowmem = pcms->max_ram_below_4g;

        if (machine->ram_size >= pcms->max_ram_below_4g) {

            if (pcmc->gigabyte_align) {
@@ -136,9 +145,6 @@ static void pc_init1(MachineState *machine, 
            pcms->above_4g_mem_size = 0;

            pcms->below_4g_mem_size = machine->ram_size;

        }



    if (xen_enabled()) {

        xen_hvm_init(pcms, &ram_memory);

    }



    pc_cpus_init(pcms);

hw/i386/pc_q35.c

+3 −0
Original line number Diff line number Diff line
@@ -94,6 +94,9 @@ static void pc_q35_init(MachineState *machine) 
    /* Handle the machine opt max-ram-below-4g.  It is basically doing

     * min(qemu limit, user limit).

     */

    if (!pcms->max_ram_below_4g) {

        pcms->max_ram_below_4g = 1ULL << 32; /* default: 4G */;

    }

    if (lowmem > pcms->max_ram_below_4g) {

        lowmem = pcms->max_ram_below_4g;

        if (machine->ram_size - lowmem > lowmem &&

xen-hvm.c

+3 −0
Original line number Diff line number Diff line
@@ -190,6 +190,9 @@ static void xen_ram_init(PCMachineState *pcms, 
    /* Handle the machine opt max-ram-below-4g.  It is basically doing

     * min(xen limit, user limit).

     */

    if (!user_lowmem) {

        user_lowmem = HVM_BELOW_4G_RAM_END; /* default */

    }

    if (HVM_BELOW_4G_RAM_END <= user_lowmem) {

        user_lowmem = HVM_BELOW_4G_RAM_END;

    }