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hw/avr: Prepare for TARGET_PAGE_SIZE > 256

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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.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2025-03-25 15:26:28 -07:00
parent 95d4f72d6a
commit 9f99072fc0
2 changed files with 33 additions and 7 deletions
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39
hw/avr/atmega.c
View file

@ -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),

1
hw/avr/atmega.h
View file

@ -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];