[Qemu-devel] [PATCH] Introduce machine specific default memory size

[Qemu-devel] [PATCH] Introduce machine specific default memory size

[Nikunj A Dadhania]

Qemu default memory of 128MB is not enough to boot spapr
guest. Introduce a property in the machine class to override the
default memory size enforced by qemu.

Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
---
 hw/ppc/spapr.c         |  1 +
 include/hw/boards.h    |  1 +
 include/hw/ppc/spapr.h |  3 +++
 vl.c                   | 12 ++++++++++++
 4 files changed, 17 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 30de25d..857035e 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1686,6 +1686,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
     mc->max_cpus = MAX_CPUS;
     mc->no_parallel = 1;
     mc->default_boot_order = NULL;
+    mc->default_ram_size = SPAPR_DEFAULT_RAM_SIZE;
     mc->kvm_type = spapr_kvm_type;
     mc->has_dynamic_sysbus = true;
 
diff --git a/include/hw/boards.h b/include/hw/boards.h
index e0a6790..9fe264f 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -106,6 +106,7 @@ struct MachineClass {
     const char *default_display;
     GlobalProperty *compat_props;
     const char *hw_version;
+    ram_addr_t default_ram_size;
 
     HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
                                            DeviceState *dev);
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 749daf4..2f83458 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -443,6 +443,9 @@ int spapr_rtas_device_tree_setup(void *fdt, hwaddr rtas_addr,
 #define SPAPR_VIO_BASE_LIOBN    0x00000000
 #define SPAPR_PCI_BASE_LIOBN    0x80000000
 
+/* Default to 1GB guest ram_size */
+#define SPAPR_DEFAULT_RAM_SIZE  (1ULL << 30)
+
 #define RTAS_ERROR_LOG_MAX      2048
 
 typedef struct sPAPRTCETable sPAPRTCETable;
diff --git a/vl.c b/vl.c
index eb89d62..dd56754 100644
--- a/vl.c
+++ b/vl.c
@@ -4053,6 +4053,18 @@ int main(int argc, char **argv, char **envp)
         exit(1);
     }
 
+    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
+        fprintf(stderr, "qemu: %s guest ram size defaulting to %ld MB\n",
+                machine_class->name,
+                machine_class->default_ram_size / (1024 * 1024));
+        ram_size = machine_class->default_ram_size;
+
+        /* if maxram size is not provided in options use machine default */
+        if (maxram_size == default_ram_size) {
+            maxram_size = machine_class->default_ram_size;
+        }
+    }
+
     /* store value for the future use */
     qemu_opt_set_number(qemu_find_opts_singleton("memory"), "size", ram_size);
 
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH] Introduce machine specific default memory size

[Markus Armbruster]

Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> writes:

> Qemu default memory of 128MB is not enough to boot spapr
> guest. Introduce a property in the machine class to override the
> default memory size enforced by qemu.
>
> Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
> ---
>  hw/ppc/spapr.c         |  1 +
>  include/hw/boards.h    |  1 +
>  include/hw/ppc/spapr.h |  3 +++
>  vl.c                   | 12 ++++++++++++
>  4 files changed, 17 insertions(+)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 30de25d..857035e 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1686,6 +1686,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
>      mc->max_cpus = MAX_CPUS;
>      mc->no_parallel = 1;
>      mc->default_boot_order = NULL;
> +    mc->default_ram_size = SPAPR_DEFAULT_RAM_SIZE;
>      mc->kvm_type = spapr_kvm_type;
>      mc->has_dynamic_sysbus = true;
>  
> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index e0a6790..9fe264f 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -106,6 +106,7 @@ struct MachineClass {
>      const char *default_display;
>      GlobalProperty *compat_props;
>      const char *hw_version;
> +    ram_addr_t default_ram_size;
>  
>      HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
>                                             DeviceState *dev);
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 749daf4..2f83458 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -443,6 +443,9 @@ int spapr_rtas_device_tree_setup(void *fdt, hwaddr rtas_addr,
>  #define SPAPR_VIO_BASE_LIOBN    0x00000000
>  #define SPAPR_PCI_BASE_LIOBN    0x80000000
>  
> +/* Default to 1GB guest ram_size */
> +#define SPAPR_DEFAULT_RAM_SIZE  (1ULL << 30)
> +
>  #define RTAS_ERROR_LOG_MAX      2048
>  
>  typedef struct sPAPRTCETable sPAPRTCETable;
> diff --git a/vl.c b/vl.c
> index eb89d62..dd56754 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -4053,6 +4053,18 @@ int main(int argc, char **argv, char **envp)
>          exit(1);
>      }
>  
> +    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
> +        fprintf(stderr, "qemu: %s guest ram size defaulting to %ld MB\n",
> +                machine_class->name,
> +                machine_class->default_ram_size / (1024 * 1024));

If the user explicitly asks for something, we either provide it
silently, or we error out.  This does neither.  Why?

> +        ram_size = machine_class->default_ram_size;
> +
> +        /* if maxram size is not provided in options use machine default */
> +        if (maxram_size == default_ram_size) {
> +            maxram_size = machine_class->default_ram_size;
> +        }
> +    }
> +
>      /* store value for the future use */
>      qemu_opt_set_number(qemu_find_opts_singleton("memory"), "size", ram_size);

Does not apply to master, please name your prerequisite patches or
rebase.

Re: [Qemu-devel] [PATCH] Introduce machine specific default memory size

[Nikunj A Dadhania]

Markus Armbruster <armbru@redhat.com> writes:

> Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> writes:
>
>> diff --git a/vl.c b/vl.c
>> index eb89d62..dd56754 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -4053,6 +4053,18 @@ int main(int argc, char **argv, char **envp)
>>          exit(1);
>>      }
>>  
>> +    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
>> +        fprintf(stderr, "qemu: %s guest ram size defaulting to %ld MB\n",
>> +                machine_class->name,
>> +                machine_class->default_ram_size / (1024 * 1024));
>
> If the user explicitly asks for something, we either provide it
> silently, or we error out.  This does neither.  Why?

In case the user has provided memory not enough to boot the machine, I
could error out. My idea was to have a sane default which is provided by
the machine.

Initially, I had just "ram_size == default_ram_size", but then it was
allowing "-m 128M" to go through. And the VM would not boot. 

This can as well be converted to an error report and fail here to boot
the VM.

>
>> +        ram_size = machine_class->default_ram_size;
>> +
>> +        /* if maxram size is not provided in options use machine default */
>> +        if (maxram_size == default_ram_size) {
>> +            maxram_size = machine_class->default_ram_size;
>> +        }
>> +    }
>> +
>>      /* store value for the future use */
>>      qemu_opt_set_number(qemu_find_opts_singleton("memory"), "size", ram_size);
>
> Does not apply to master, please name your prerequisite patches or
> rebase.


Rebased patch:


    Introduce machine specific default memory size
    
    Qemu default memory of 128MB is not enough to boot sPAPR
    guest. Introduce a member in the machine class to override the default
    memory size enforced by qemu.
    
    Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 23cde20..f6b1137 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1738,6 +1738,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
     mc->max_cpus = MAX_CPUS;
     mc->no_parallel = 1;
     mc->default_boot_order = NULL;
+    mc->default_ram_size = SPAPR_DEFAULT_RAM_SIZE;
     mc->kvm_type = spapr_kvm_type;
     mc->has_dynamic_sysbus = true;
 
diff --git a/include/hw/boards.h b/include/hw/boards.h
index 3ddc449..b2b4698 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -108,6 +108,7 @@ struct MachineClass {
     const char *default_display;
     GlobalProperty *compat_props;
     const char *hw_version;
+    ram_addr_t default_ram_size;
 
     HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
                                            DeviceState *dev);
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 716bff4..d401dd0 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -444,6 +444,9 @@ int spapr_rtas_device_tree_setup(void *fdt, hwaddr rtas_addr,
 #define SPAPR_VIO_BASE_LIOBN    0x00000000
 #define SPAPR_PCI_BASE_LIOBN    0x80000000
 
+/* Default to 1GB guest ram_size */
+#define SPAPR_DEFAULT_RAM_SIZE  (1ULL << 30)
+
 #define RTAS_ERROR_LOG_MAX      2048
 
 typedef struct sPAPRTCETable sPAPRTCETable;
diff --git a/vl.c b/vl.c
index 801d487..4519ccc 100644
--- a/vl.c
+++ b/vl.c
@@ -2684,6 +2684,18 @@ static void set_memory_options(uint64_t *ram_slots, ram_addr_t *maxram_size)
         exit(EXIT_FAILURE);
     }
 
+    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
+        fprintf(stderr, "qemu: %s guest ram size defaulting to %ld MB\n",
+                machine_class->name,
+                machine_class->default_ram_size / (1024 * 1024));
+        ram_size = machine_class->default_ram_size;
+
+        /* if maxram size is not provided in options use machine default */
+        if (maxram_size == default_ram_size) {
+            maxram_size = machine_class->default_ram_size;
+        }
+    }
+
     /* store value for the future use */
     qemu_opt_set_number(opts, "size", ram_size, &error_abort);
     *maxram_size = ram_size;

Re: [Qemu-devel] [PATCH] Introduce machine specific default memory size

[Thomas Huth]

On Wed, 04 Mar 2015 14:00:17 +0530
Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:

> Markus Armbruster <armbru@redhat.com> writes:
> 
> > Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> writes:
> >
> >> diff --git a/vl.c b/vl.c
> >> index eb89d62..dd56754 100644
> >> --- a/vl.c
> >> +++ b/vl.c
> >> @@ -4053,6 +4053,18 @@ int main(int argc, char **argv, char **envp)
> >>          exit(1);
> >>      }
> >>  
> >> +    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
> >> +        fprintf(stderr, "qemu: %s guest ram size defaulting to %ld MB\n",
> >> +                machine_class->name,
> >> +                machine_class->default_ram_size / (1024 * 1024));
> >
> > If the user explicitly asks for something, we either provide it
> > silently, or we error out.  This does neither.  Why?
> 
> In case the user has provided memory not enough to boot the machine, I
> could error out. My idea was to have a sane default which is provided by
> the machine.
> 
> Initially, I had just "ram_size == default_ram_size", but then it was
> allowing "-m 128M" to go through. And the VM would not boot. 
> 
> This can as well be converted to an error report and fail here to boot
> the VM.

What does exactly fail with 128MB? Linux? SLOF? IIRC, a couple of years
ago, 128MB were enough to boot a Linux guest in the spapr machine...

 Thomas

Re: [Qemu-devel] [PATCH] Introduce machine specific default memory size

[Nikunj A Dadhania]

Thomas Huth <thuth@linux.vnet.ibm.com> writes:

> On Wed, 04 Mar 2015 14:00:17 +0530
> Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:
>
>> Markus Armbruster <armbru@redhat.com> writes:
>> 
>> > Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> writes:
>> >
>> >> diff --git a/vl.c b/vl.c
>> >> index eb89d62..dd56754 100644
>> >> --- a/vl.c
>> >> +++ b/vl.c
>> >> @@ -4053,6 +4053,18 @@ int main(int argc, char **argv, char **envp)
>> >>          exit(1);
>> >>      }
>> >>  
>> >> +    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
>> >> +        fprintf(stderr, "qemu: %s guest ram size defaulting to %ld MB\n",
>> >> +                machine_class->name,
>> >> +                machine_class->default_ram_size / (1024 * 1024));
>> >
>> > If the user explicitly asks for something, we either provide it
>> > silently, or we error out.  This does neither.  Why?
>> 
>> In case the user has provided memory not enough to boot the machine, I
>> could error out. My idea was to have a sane default which is provided by
>> the machine.
>> 
>> Initially, I had just "ram_size == default_ram_size", but then it was
>> allowing "-m 128M" to go through. And the VM would not boot. 
>> 
>> This can as well be converted to an error report and fail here to boot
>> the VM.
>
> What does exactly fail with 128MB? Linux? 

Linux kernel, and not much info as well on the console.

Regards
Nikunj

Re: [Qemu-devel] [PATCH] Introduce machine specific default memory size

[Thomas Huth]

On Wed, 04 Mar 2015 14:34:27 +0530
Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:

> Thomas Huth <thuth@linux.vnet.ibm.com> writes:
> 
> > On Wed, 04 Mar 2015 14:00:17 +0530
> > Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:
> >
> >> Markus Armbruster <armbru@redhat.com> writes:
> >> 
> >> > Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> writes:
> >> >
> >> >> diff --git a/vl.c b/vl.c
> >> >> index eb89d62..dd56754 100644
> >> >> --- a/vl.c
> >> >> +++ b/vl.c
> >> >> @@ -4053,6 +4053,18 @@ int main(int argc, char **argv, char **envp)
> >> >>          exit(1);
> >> >>      }
> >> >>  
> >> >> +    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
> >> >> +        fprintf(stderr, "qemu: %s guest ram size defaulting to %ld MB\n",
> >> >> +                machine_class->name,
> >> >> +                machine_class->default_ram_size / (1024 * 1024));
> >> >
> >> > If the user explicitly asks for something, we either provide it
> >> > silently, or we error out.  This does neither.  Why?
> >> 
> >> In case the user has provided memory not enough to boot the machine, I
> >> could error out. My idea was to have a sane default which is provided by
> >> the machine.
> >> 
> >> Initially, I had just "ram_size == default_ram_size", but then it was
> >> allowing "-m 128M" to go through. And the VM would not boot. 
> >> 
> >> This can as well be converted to an error report and fail here to boot
> >> the VM.
> >
> > What does exactly fail with 128MB? Linux? 
> 
> Linux kernel, and not much info as well on the console.

Ok, but then I think it should still be possible to specify -m 128M on
the command line - in case the user wants to run an older Linux which
still works fine with that amount of memory.

 Thomas

Re: [Qemu-devel] [PATCH] Introduce machine specific default memory size

[Nikunj A Dadhania]

Thomas Huth <thuth@linux.vnet.ibm.com> writes:

> On Wed, 04 Mar 2015 14:34:27 +0530
> Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:
>
>> Thomas Huth <thuth@linux.vnet.ibm.com> writes:
>> 
>> > On Wed, 04 Mar 2015 14:00:17 +0530
>> > Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:
>> >
>> >> Markus Armbruster <armbru@redhat.com> writes:
>> >> 
>> >> > Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> writes:
>> >> >
>> >> >> diff --git a/vl.c b/vl.c
>> >> >> index eb89d62..dd56754 100644
>> >> >> --- a/vl.c
>> >> >> +++ b/vl.c
>> >> >> @@ -4053,6 +4053,18 @@ int main(int argc, char **argv, char **envp)
>> >> >>          exit(1);
>> >> >>      }
>> >> >>  
>> >> >> +    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
>> >> >> +        fprintf(stderr, "qemu: %s guest ram size defaulting to %ld MB\n",
>> >> >> +                machine_class->name,
>> >> >> +                machine_class->default_ram_size / (1024 * 1024));
>> >> >
>> >> > If the user explicitly asks for something, we either provide it
>> >> > silently, or we error out.  This does neither.  Why?
>> >> 
>> >> In case the user has provided memory not enough to boot the machine, I
>> >> could error out. My idea was to have a sane default which is provided by
>> >> the machine.
>> >> 
>> >> Initially, I had just "ram_size == default_ram_size", but then it was
>> >> allowing "-m 128M" to go through. And the VM would not boot. 
>> >> 
>> >> This can as well be converted to an error report and fail here to boot
>> >> the VM.
>> >
>> > What does exactly fail with 128MB? Linux? 
>> 
>> Linux kernel, and not much info as well on the console.
>
> Ok, but then I think it should still be possible to specify -m 128M on
> the command line - in case the user wants to run an older Linux which
> still works fine with that amount of memory.

But how do we distinguish whether its old/new kernel in the distro?

And the older kernel will boot with more memory, while the reverse isnt
true.

Regards
Nikunj

Re: [Qemu-devel] [PATCH] Introduce machine specific default memory size

[Thomas Huth]

On Wed, 04 Mar 2015 14:59:13 +0530
Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:

> Thomas Huth <thuth@linux.vnet.ibm.com> writes:
> 
> > On Wed, 04 Mar 2015 14:34:27 +0530
> > Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:
> >
> >> Thomas Huth <thuth@linux.vnet.ibm.com> writes:
> >> 
> >> > On Wed, 04 Mar 2015 14:00:17 +0530
> >> > Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:
> >> >
> >> >> Markus Armbruster <armbru@redhat.com> writes:
> >> >> 
> >> >> > Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> writes:
> >> >> >
> >> >> >> diff --git a/vl.c b/vl.c
> >> >> >> index eb89d62..dd56754 100644
> >> >> >> --- a/vl.c
> >> >> >> +++ b/vl.c
> >> >> >> @@ -4053,6 +4053,18 @@ int main(int argc, char **argv, char **envp)
> >> >> >>          exit(1);
> >> >> >>      }
> >> >> >>  
> >> >> >> +    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
> >> >> >> +        fprintf(stderr, "qemu: %s guest ram size defaulting to %ld MB\n",
> >> >> >> +                machine_class->name,
> >> >> >> +                machine_class->default_ram_size / (1024 * 1024));
> >> >> >
> >> >> > If the user explicitly asks for something, we either provide it
> >> >> > silently, or we error out.  This does neither.  Why?
> >> >> 
> >> >> In case the user has provided memory not enough to boot the machine, I
> >> >> could error out. My idea was to have a sane default which is provided by
> >> >> the machine.
> >> >> 
> >> >> Initially, I had just "ram_size == default_ram_size", but then it was
> >> >> allowing "-m 128M" to go through. And the VM would not boot. 
> >> >> 
> >> >> This can as well be converted to an error report and fail here to boot
> >> >> the VM.
> >> >
> >> > What does exactly fail with 128MB? Linux? 
> >> 
> >> Linux kernel, and not much info as well on the console.
> >
> > Ok, but then I think it should still be possible to specify -m 128M on
> > the command line - in case the user wants to run an older Linux which
> > still works fine with that amount of memory.
> 
> But how do we distinguish whether its old/new kernel in the distro?
> 
> And the older kernel will boot with more memory, while the reverse isnt
> true.

True, and it's IMHO certainly ok to increase the default memory size -
I just wanted to say that you should not disallow "-m 128M" in case the
users know what they are doing.

 Thomas

Re: [Qemu-devel] [PATCH] Introduce machine specific default memory size

[Nikunj A Dadhania]

Thomas Huth <thuth@linux.vnet.ibm.com> writes:

> On Wed, 04 Mar 2015 14:59:13 +0530
> Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:
>
>> Thomas Huth <thuth@linux.vnet.ibm.com> writes:
>> 
>> > On Wed, 04 Mar 2015 14:34:27 +0530
>> > Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:
>> >
>> >> Thomas Huth <thuth@linux.vnet.ibm.com> writes:
>> >> 
>> >> > On Wed, 04 Mar 2015 14:00:17 +0530
>> >> > Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:
>> >> >
>> >> >> Markus Armbruster <armbru@redhat.com> writes:
>> >> >> 
>> >> >> > Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> writes:
>> >> >> >
>> >> >> >> diff --git a/vl.c b/vl.c
>> >> >> >> index eb89d62..dd56754 100644
>> >> >> >> --- a/vl.c
>> >> >> >> +++ b/vl.c
>> >> >> >> @@ -4053,6 +4053,18 @@ int main(int argc, char **argv, char **envp)
>> >> >> >>          exit(1);
>> >> >> >>      }
>> >> >> >>  
>> >> >> >> +    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
>> >> >> >> +        fprintf(stderr, "qemu: %s guest ram size defaulting to %ld MB\n",
>> >> >> >> +                machine_class->name,
>> >> >> >> +                machine_class->default_ram_size / (1024 * 1024));
>> >> >> >
>> >> >> > If the user explicitly asks for something, we either provide it
>> >> >> > silently, or we error out.  This does neither.  Why?
>> >> >> 
>> >> >> In case the user has provided memory not enough to boot the machine, I
>> >> >> could error out. My idea was to have a sane default which is provided by
>> >> >> the machine.
>> >> >> 
>> >> >> Initially, I had just "ram_size == default_ram_size", but then it was
>> >> >> allowing "-m 128M" to go through. And the VM would not boot. 
>> >> >> 
>> >> >> This can as well be converted to an error report and fail here to boot
>> >> >> the VM.
>> >> >
>> >> > What does exactly fail with 128MB? Linux? 
>> >> 
>> >> Linux kernel, and not much info as well on the console.
>> >
>> > Ok, but then I think it should still be possible to specify -m 128M on
>> > the command line - in case the user wants to run an older Linux which
>> > still works fine with that amount of memory.
>> 
>> But how do we distinguish whether its old/new kernel in the distro?
>> 
>> And the older kernel will boot with more memory, while the reverse isnt
>> true.
>
> True, and it's IMHO certainly ok to increase the default memory size -

> I just wanted to say that you should not disallow "-m 128M" in case the
> users know what they are doing.

That becomes a little bit tricky, as 128MB can come from
default_ram_size and from the user as well. 

So here I am only changing the machine class for sPAPR. I have tried few
distro installations and none of them boot with qemu default
memory(128MB). Moreover, the installer kernel does not tell what went
wrong. It silently goes till a point and is stuck.

Regards
Nikunj

Re: [Qemu-devel] [Qemu-ppc] [PATCH] Introduce machine specific default memory size

[Nikunj A Dadhania]

Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> writes:

> Markus Armbruster <armbru@redhat.com> writes:
>
>> Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> writes:
>>
>>> diff --git a/vl.c b/vl.c
>>> index eb89d62..dd56754 100644
>>> --- a/vl.c
>>> +++ b/vl.c
>>> @@ -4053,6 +4053,18 @@ int main(int argc, char **argv, char **envp)
>>>          exit(1);
>>>      }
>>>  
>>> +    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
>>> +        fprintf(stderr, "qemu: %s guest ram size defaulting to %ld MB\n",
>>> +                machine_class->name,
>>> +                machine_class->default_ram_size / (1024 * 1024));
>>
>> If the user explicitly asks for something, we either provide it
>> silently, or we error out.  This does neither.  Why?
>
> In case the user has provided memory not enough to boot the machine, I
> could error out. My idea was to have a sane default which is provided by
> the machine.
>
> Initially, I had just "ram_size == default_ram_size", but then it was
> allowing "-m 128M" to go through. And the VM would not boot. 
>
> This can as well be converted to an error report and fail here to boot
> the VM.
>
>>
>>> +        ram_size = machine_class->default_ram_size;
>>> +
>>> +        /* if maxram size is not provided in options use machine default */
>>> +        if (maxram_size == default_ram_size) {
>>> +            maxram_size = machine_class->default_ram_size;
>>> +        }
>>> +    }
>>> +
>>>      /* store value for the future use */
>>>      qemu_opt_set_number(qemu_find_opts_singleton("memory"), "size", ram_size);
>>
>> Does not apply to master, please name your prerequisite patches or
>> rebase.
>
>
> Rebased patch:
>
>
>     Introduce machine specific default memory size
>     
>     Qemu default memory of 128MB is not enough to boot sPAPR
>     guest. Introduce a member in the machine class to override the default
>     memory size enforced by qemu.
>     
>     Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>

Ignore this, will be sending a v2