If i/o does not cover the entire first page, allocate a portion
of ram as an i/o device, so that the entire first page is i/o.
While memory_region_init_ram_device_ptr is happy to allocate
the RAMBlock, it does not register the ram for migration.
Do this by hand.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
hw/avr/atmega.h | 1 +
hw/avr/atmega.c | 39 ++++++++++++++++++++++++++++++++-------
2 files changed, 33 insertions(+), 7 deletions(-)
diff --git a/hw/avr/atmega.h b/hw/avr/atmega.h
index a99ee15c7e..9ac4678231 100644
--- a/hw/avr/atmega.h
+++ b/hw/avr/atmega.h
@@ -41,6 +41,7 @@ struct AtmegaMcuState {
MemoryRegion flash;
MemoryRegion eeprom;
MemoryRegion sram;
+ MemoryRegion sram_io;
DeviceState *io;
AVRMaskState pwr[POWER_MAX];
AVRUsartState usart[USART_MAX];
diff --git a/hw/avr/atmega.c b/hw/avr/atmega.c
index f6844bf118..11fab184de 100644
--- a/hw/avr/atmega.c
+++ b/hw/avr/atmega.c
@@ -19,6 +19,7 @@
#include "hw/sysbus.h"
#include "qom/object.h"
#include "hw/misc/unimp.h"
+#include "migration/vmstate.h"
#include "atmega.h"
enum AtmegaPeripheral {
@@ -224,8 +225,6 @@ static void atmega_realize(DeviceState *dev, Error **errp)
char *devname;
size_t i;
- assert(mc->io_size <= 0x200);
-
if (!s->xtal_freq_hz) {
error_setg(errp, "\"xtal-frequency-hz\" property must be provided.");
return;
@@ -240,11 +239,37 @@ static void atmega_realize(DeviceState *dev, Error **errp)
qdev_realize(DEVICE(&s->cpu), NULL, &error_abort);
cpudev = DEVICE(&s->cpu);
- /* SRAM */
- memory_region_init_ram(&s->sram, OBJECT(dev), "sram", mc->sram_size,
- &error_abort);
- memory_region_add_subregion(get_system_memory(),
- OFFSET_DATA + mc->io_size, &s->sram);
+ /*
+ * SRAM
+ *
+ * Softmmu is not able mix i/o and ram on the same page.
+ * Therefore in all cases, the first page exclusively contains i/o.
+ *
+ * If the MCU's i/o region matches the page size, then we can simply
+ * allocate all ram starting at the second page. Otherwise, we must
+ * allocate some ram as i/o to complete the first page.
+ */
+ assert(mc->io_size == 0x100 || mc->io_size == 0x200);
+ if (mc->io_size >= TARGET_PAGE_SIZE) {
+ memory_region_init_ram(&s->sram, OBJECT(dev), "sram", mc->sram_size,
+ &error_abort);
+ memory_region_add_subregion(get_system_memory(),
+ OFFSET_DATA + mc->io_size, &s->sram);
+ } else {
+ int sram_io_size = TARGET_PAGE_SIZE - mc->io_size;
+ void *sram_io_mem = g_malloc0(sram_io_size);
+
+ memory_region_init_ram_device_ptr(&s->sram_io, OBJECT(dev), "sram-as-io",
+ sram_io_size, sram_io_mem);
+ memory_region_add_subregion(get_system_memory(),
+ OFFSET_DATA + mc->io_size, &s->sram_io);
+ vmstate_register_ram(&s->sram_io, dev);
+
+ memory_region_init_ram(&s->sram, OBJECT(dev), "sram",
+ mc->sram_size - sram_io_size, &error_abort);
+ memory_region_add_subregion(get_system_memory(),
+ OFFSET_DATA + TARGET_PAGE_SIZE, &s->sram);
+ }
/* Flash */
memory_region_init_rom(&s->flash, OBJECT(dev),
--
2.43.0On 25/3/25 23:44, Richard Henderson wrote:
> If i/o does not cover the entire first page, allocate a portion
> of ram as an i/o device, so that the entire first page is i/o.
>
> While memory_region_init_ram_device_ptr is happy to allocate
> the RAMBlock, it does not register the ram for migration.
> Do this by hand.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> hw/avr/atmega.h | 1 +
> hw/avr/atmega.c | 39 ++++++++++++++++++++++++++++++++-------
> 2 files changed, 33 insertions(+), 7 deletions(-)
>
> diff --git a/hw/avr/atmega.h b/hw/avr/atmega.h
> index a99ee15c7e..9ac4678231 100644
> --- a/hw/avr/atmega.h
> +++ b/hw/avr/atmega.h
> @@ -41,6 +41,7 @@ struct AtmegaMcuState {
> MemoryRegion flash;
> MemoryRegion eeprom;
> MemoryRegion sram;
> + MemoryRegion sram_io;
> DeviceState *io;
> AVRMaskState pwr[POWER_MAX];
> AVRUsartState usart[USART_MAX];
> @@ -240,11 +239,37 @@ static void atmega_realize(DeviceState *dev, Error **errp)
> qdev_realize(DEVICE(&s->cpu), NULL, &error_abort);
> cpudev = DEVICE(&s->cpu);
>
> - /* SRAM */
> - memory_region_init_ram(&s->sram, OBJECT(dev), "sram", mc->sram_size,
> - &error_abort);
> - memory_region_add_subregion(get_system_memory(),
> - OFFSET_DATA + mc->io_size, &s->sram);
> + /*
> + * SRAM
> + *
> + * Softmmu is not able mix i/o and ram on the same page.
> + * Therefore in all cases, the first page exclusively contains i/o.
> + *
> + * If the MCU's i/o region matches the page size, then we can simply
> + * allocate all ram starting at the second page. Otherwise, we must
> + * allocate some ram as i/o to complete the first page.
> + */
> + assert(mc->io_size == 0x100 || mc->io_size == 0x200);
> + if (mc->io_size >= TARGET_PAGE_SIZE) {
> + memory_region_init_ram(&s->sram, OBJECT(dev), "sram", mc->sram_size,
> + &error_abort);
> + memory_region_add_subregion(get_system_memory(),
> + OFFSET_DATA + mc->io_size, &s->sram);
> + } else {
> + int sram_io_size = TARGET_PAGE_SIZE - mc->io_size;
> + void *sram_io_mem = g_malloc0(sram_io_size);
Please declare sram_io_mem in AtmegaMcuState, after sram_io.
> +
> + memory_region_init_ram_device_ptr(&s->sram_io, OBJECT(dev), "sram-as-io",
> + sram_io_size, sram_io_mem);
> + memory_region_add_subregion(get_system_memory(),
> + OFFSET_DATA + mc->io_size, &s->sram_io);
> + vmstate_register_ram(&s->sram_io, dev);
> +
> + memory_region_init_ram(&s->sram, OBJECT(dev), "sram",
> + mc->sram_size - sram_io_size, &error_abort);
> + memory_region_add_subregion(get_system_memory(),
> + OFFSET_DATA + TARGET_PAGE_SIZE, &s->sram);
> + }
On 3/27/25 13:24, Philippe Mathieu-Daudé wrote:
> On 25/3/25 23:44, Richard Henderson wrote:
>> If i/o does not cover the entire first page, allocate a portion
>> of ram as an i/o device, so that the entire first page is i/o.
>>
>> While memory_region_init_ram_device_ptr is happy to allocate
>> the RAMBlock, it does not register the ram for migration.
>> Do this by hand.
>>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>> hw/avr/atmega.h | 1 +
>> hw/avr/atmega.c | 39 ++++++++++++++++++++++++++++++++-------
>> 2 files changed, 33 insertions(+), 7 deletions(-)
>>
>> diff --git a/hw/avr/atmega.h b/hw/avr/atmega.h
>> index a99ee15c7e..9ac4678231 100644
>> --- a/hw/avr/atmega.h
>> +++ b/hw/avr/atmega.h
>> @@ -41,6 +41,7 @@ struct AtmegaMcuState {
>> MemoryRegion flash;
>> MemoryRegion eeprom;
>> MemoryRegion sram;
>> + MemoryRegion sram_io;
>> DeviceState *io;
>> AVRMaskState pwr[POWER_MAX];
>> AVRUsartState usart[USART_MAX];
>
>> @@ -240,11 +239,37 @@ static void atmega_realize(DeviceState *dev, Error **errp)
>> qdev_realize(DEVICE(&s->cpu), NULL, &error_abort);
>> cpudev = DEVICE(&s->cpu);
>> - /* SRAM */
>> - memory_region_init_ram(&s->sram, OBJECT(dev), "sram", mc->sram_size,
>> - &error_abort);
>> - memory_region_add_subregion(get_system_memory(),
>> - OFFSET_DATA + mc->io_size, &s->sram);
>> + /*
>> + * SRAM
>> + *
>> + * Softmmu is not able mix i/o and ram on the same page.
>> + * Therefore in all cases, the first page exclusively contains i/o.
>> + *
>> + * If the MCU's i/o region matches the page size, then we can simply
>> + * allocate all ram starting at the second page. Otherwise, we must
>> + * allocate some ram as i/o to complete the first page.
>> + */
>> + assert(mc->io_size == 0x100 || mc->io_size == 0x200);
>> + if (mc->io_size >= TARGET_PAGE_SIZE) {
>> + memory_region_init_ram(&s->sram, OBJECT(dev), "sram", mc->sram_size,
>> + &error_abort);
>> + memory_region_add_subregion(get_system_memory(),
>> + OFFSET_DATA + mc->io_size, &s->sram);
>> + } else {
>> + int sram_io_size = TARGET_PAGE_SIZE - mc->io_size;
>> + void *sram_io_mem = g_malloc0(sram_io_size);
>
> Please declare sram_io_mem in AtmegaMcuState, after sram_io.
Why?
>> +
>> + memory_region_init_ram_device_ptr(&s->sram_io, OBJECT(dev), "sram-as-io",
>> + sram_io_size, sram_io_mem);
After this, it's accessible as
s->sram_io->ram_block->host
It wouldn't be accessed in any other way, surely?
r~
On 3/25/25 15:44, Richard Henderson wrote:
> If i/o does not cover the entire first page, allocate a portion
> of ram as an i/o device, so that the entire first page is i/o.
>
> While memory_region_init_ram_device_ptr is happy to allocate
> the RAMBlock, it does not register the ram for migration.
> Do this by hand.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> hw/avr/atmega.h | 1 +
> hw/avr/atmega.c | 39 ++++++++++++++++++++++++++++++++-------
> 2 files changed, 33 insertions(+), 7 deletions(-)
>
> diff --git a/hw/avr/atmega.h b/hw/avr/atmega.h
> index a99ee15c7e..9ac4678231 100644
> --- a/hw/avr/atmega.h
> +++ b/hw/avr/atmega.h
> @@ -41,6 +41,7 @@ struct AtmegaMcuState {
> MemoryRegion flash;
> MemoryRegion eeprom;
> MemoryRegion sram;
> + MemoryRegion sram_io;
> DeviceState *io;
> AVRMaskState pwr[POWER_MAX];
> AVRUsartState usart[USART_MAX];
> diff --git a/hw/avr/atmega.c b/hw/avr/atmega.c
> index f6844bf118..11fab184de 100644
> --- a/hw/avr/atmega.c
> +++ b/hw/avr/atmega.c
> @@ -19,6 +19,7 @@
> #include "hw/sysbus.h"
> #include "qom/object.h"
> #include "hw/misc/unimp.h"
> +#include "migration/vmstate.h"
> #include "atmega.h"
>
> enum AtmegaPeripheral {
> @@ -224,8 +225,6 @@ static void atmega_realize(DeviceState *dev, Error **errp)
> char *devname;
> size_t i;
>
> - assert(mc->io_size <= 0x200);
> -
> if (!s->xtal_freq_hz) {
> error_setg(errp, "\"xtal-frequency-hz\" property must be provided.");
> return;
> @@ -240,11 +239,37 @@ static void atmega_realize(DeviceState *dev, Error **errp)
> qdev_realize(DEVICE(&s->cpu), NULL, &error_abort);
> cpudev = DEVICE(&s->cpu);
>
> - /* SRAM */
> - memory_region_init_ram(&s->sram, OBJECT(dev), "sram", mc->sram_size,
> - &error_abort);
> - memory_region_add_subregion(get_system_memory(),
> - OFFSET_DATA + mc->io_size, &s->sram);
> + /*
> + * SRAM
> + *
> + * Softmmu is not able mix i/o and ram on the same page.
> + * Therefore in all cases, the first page exclusively contains i/o.
> + *
> + * If the MCU's i/o region matches the page size, then we can simply
> + * allocate all ram starting at the second page. Otherwise, we must
> + * allocate some ram as i/o to complete the first page.
> + */
> + assert(mc->io_size == 0x100 || mc->io_size == 0x200);
> + if (mc->io_size >= TARGET_PAGE_SIZE) {
> + memory_region_init_ram(&s->sram, OBJECT(dev), "sram", mc->sram_size,
> + &error_abort);
> + memory_region_add_subregion(get_system_memory(),
> + OFFSET_DATA + mc->io_size, &s->sram);
> + } else {
> + int sram_io_size = TARGET_PAGE_SIZE - mc->io_size;
> + void *sram_io_mem = g_malloc0(sram_io_size);
> +
> + memory_region_init_ram_device_ptr(&s->sram_io, OBJECT(dev), "sram-as-io",
> + sram_io_size, sram_io_mem);
> + memory_region_add_subregion(get_system_memory(),
> + OFFSET_DATA + mc->io_size, &s->sram_io);
> + vmstate_register_ram(&s->sram_io, dev);
> +
> + memory_region_init_ram(&s->sram, OBJECT(dev), "sram",
> + mc->sram_size - sram_io_size, &error_abort);
> + memory_region_add_subregion(get_system_memory(),
> + OFFSET_DATA + TARGET_PAGE_SIZE, &s->sram);
> + }
>
> /* Flash */
> memory_region_init_rom(&s->flash, OBJECT(dev),
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
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