Re: [PATCH v2] ppc/pnv: Set default RAM size to 1 GB

[Greg Kurz]

On Fri, 29 Jan 2021 12:17:19 +0100
Cédric Le Goater <clg@kaod.org> wrote:

> The memory layout of the PowerNV machine is defined as :
> 
>   #define KERNEL_LOAD_BASE    ((void *)0x20000000)
>   #define KERNEL_LOAD_SIZE    0x08000000
> 
>   #define INITRAMFS_LOAD_BASE KERNEL_LOAD_BASE + KERNEL_LOAD_SIZE
>   #define INITRAMFS_LOAD_SIZE 0x08000000
> 
>   #define SKIBOOT_BASE                0x30000000
>   #define SKIBOOT_SIZE                0x01c10000
> 
>   #define CPU_STACKS_BASE     (SKIBOOT_BASE + SKIBOOT_SIZE)
>   #define STACK_SHIFT         15
>   #define STACK_SIZE          (1 << STACK_SHIFT)
> 
> The overall size of the CPU stacks is (max PIR + 1) * 32K and the
> machine easily reaches 800MB of minimum required RAM.
> 
> Any value below will result in a skiboot crash :
> 
>     [    0.034949905,3] MEM: Partial overlap detected between regions:
>     [    0.034959039,3] MEM: ibm,firmware-stacks [0x31c10000-0x3a450000] (new)
>     [    0.034968576,3] MEM: ibm,firmware-allocs-memory@0 
> [0x31c10000-0x38400000]
>     [    0.034980367,3] Out of memory adding skiboot reserved areas
>     [    0.035074945,3] ***********************************************
>     [    0.035093627,3] < assert failed at core/mem_region.c:1129 >
>     [    0.035104247,3]     .
>     [    0.035108025,3]      .
>     [    0.035111651,3]       .
>     [    0.035115231,3]         OO__)
>     [    0.035119198,3]        <"__/
>     [    0.035122980,3]         ^ ^
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  hw/ppc/pnv.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
> index 50810df83815..77af846cdfea 100644
> --- a/hw/ppc/pnv.c
> +++ b/hw/ppc/pnv.c
> @@ -21,6 +21,7 @@
>  #include "qemu-common.h"
>  #include "qemu/datadir.h"
>  #include "qemu/units.h"
> +#include "qemu/cutils.h"
>  #include "qapi/error.h"
>  #include "sysemu/qtest.h"
>  #include "sysemu/sysemu.h"
> @@ -725,8 +726,11 @@ static void pnv_init(MachineState *machine)
>      DeviceState *dev;
>  
>      /* allocate RAM */
> -    if (machine->ram_size < (1 * GiB)) {
> -        warn_report("skiboot may not work with < 1GB of RAM");
> +    if (machine->ram_size < mc->default_ram_size) {
> +        char *sz = size_to_str(mc->default_ram_size);
> +        error_report("Invalid RAM size, should be bigger than %s", sz);
> +        g_free(sz);

FWIW you could even not call g_free() at all since this is an
exit path and this code is unlikely to be reused differently,
or stay clean and tag 'sz' with g_autofree as recommended in
CODING_STYLE.

Anyway, this is definitely an improvement so:

Reviewed-by: Greg Kurz <groug@kaod.org>

> +        exit(EXIT_FAILURE);
>      }
>      memory_region_add_subregion(get_system_memory(), 0, machine->ram);
>  
> @@ -1994,7 +1998,7 @@ static void pnv_machine_class_init(ObjectClass *oc, 
> void *data)
>       * RAM defaults to less than 2048 for 32-bit hosts, and large
>       * enough to fit the maximum initrd size at it's load address
>       */
> -    mc->default_ram_size = INITRD_LOAD_ADDR + INITRD_MAX_SIZE;
> +    mc->default_ram_size = 1 * GiB;
>      mc->default_ram_id = "pnv.ram";
>      ispc->print_info = pnv_pic_print_info;
>      nc->nmi_monitor_handler = pnv_nmi;