Hi Ashraf,
On 04/05/24 12:45, Muzammil Ashraf wrote:
Hi All,
I am debugging a PCI subsystem. I saw callbacks registered here to
catch the pcie config read/write request at hw/pci/pci_host.c:201. How
can I make my subregion to overlap this area and How to receive those
pcie config read/write requests to my callbacks?
Can go through this doc:
https://www.qemu.org/docs/master/devel/memory.html#overlapping-regions-and-priority
Normally the callbacks you mentioned will be registered on a
MemoryRegion. You can create your own MemoryRegion, and set your custom
.read, .write callbacks.
And setting the MemoryRegion's priority as a big positive number.
FWIW, had did something like this in past:
+static uint64_t adi_region_read(void *chip10, hwaddr addr, unsigned size) {
+ // your code
+}
+
+static void adi_region_write(void *chip10, hwaddr addr, uint64_t value,
unsigned size) {
+ // your code
+}
+
+static const MemoryRegionOps adi_region_ops = {
+ .read = adi_region_read,
+ .write = adi_region_write,
+ .endianness = DEVICE_BIG_ENDIAN,
+ .impl = {
+ .min_access_size = 4,
+ .max_access_size = 4,
+ },
+};
+
+ static hwaddr ADI_REGION_BASE = 0x0006010000000000ull + 0x100;
+
+ memory_region_init_io(&chip10->adi_region, OBJECT(chip10),
&adi_region_ops, chip10, "custom region: adityag", 0x100);
+ memory_region_add_subregion(get_system_memory(), ADI_REGION_BASE,
&chip10->adi_region);
Instead of 'get_system_memory', you will have to see what is the PCI
config region a subregion of.
Then, set the MemoryRegion's priority to some big number.
Then, you can verify if your overlapping was successful, with something
like this:
+ MemoryRegion *mr = address_space_translate(&address_space_memory,
ADI_REGION_BASE, &xlat, &l, false, MEMTXATTRS_UNSPECIFIED);
or
+ cpu_physical_memory_read(ADI_REGION_BASE, &val, 4);
1st should return your MemoryRegion, and second one should call your
.read callback.
Thanks,
Aditya Gupta
