Hi @KChar.1 ,
I would like to know, why you want to increase the number of vring buffer and why you do not just increase the size of the buffer, like in your previous post? https://community.st.com/s/question/0D53W00000qwjyiSAA/increased-1024-rpmsg-buffer-size-will-fail-on-mailbox-vdev-declaration
Anyway, I was able to realize the modification on my stm32mp157f-dk2 board with success, by increasing the VRING_NUM_BUFFS from 16 to 32.
You only need to modify the define in openamp_conf.h
#define VRING_NUM_BUFFS 32 /* number of rpmsg buffer */
Then the modifications will be propagated to the linux automatically, thanks to the shared resource table. Defined in rsc_table.c in M4.
CONST struct shared_resource_table __resource __attribute__((used)) resource_table = {
/* Vring rsc entry - part of vdev rsc entry */
.vring0 = {VRING_TX_ADDRESS, VRING_ALIGNMENT, VRING_NUM_BUFFS, VRING0_ID, 0},
.vring1 = {VRING_RX_ADDRESS, VRING_ALIGNMENT, VRING_NUM_BUFFS, VRING1_ID, 0},
On linux side, when the driver virtio is probed, it will get its information from the shared resource table, previously filled by the M4 core.
This is done inside the file drivers/virtio/virtio_ring.c
On M4 side, remember to increase the area in the dts. This is my configuration with 32 buffers of 512 bytes :
vdev0vring0:vdev0vring0@10040000{
compatible = "shared-dma-pool";
reg = <0x10040000 0x2000>;
no-map;
};
vdev0vring1:vdev0vring1@10042000{
compatible = "shared-dma-pool";
reg = <0x10042000 0x2000>;
no-map;
};
vdev0buffer:vdev0buffer@10044000{
compatible = "shared-dma-pool";
reg = <0x10044000 0x8000>;
no-map;
};
In your case, since you increased the size of the buffers from 512 to 1024, please update the dts accordingly.
Then the final modifications is the linker file of M4. Where the ipc area length must be equal to the three areas defined in the dts.
In my case 0x2000 + 0x2000 + 0x8000 = 0xA000, but modify it regarding your dts.
RAM2_ipc_shm (xrw) : ORIGIN = 0x10040000, LENGTH = 0x0000A000
And it should works!
Now you can verify your modifications thanks to /sys/kernel/debug.
Once your board boots, you can:
cat /sys/kernel/debug/remoteproc/remoteproc0/resource_table
To verify that you allocated 32 buffers for each side RX/TX
Number of buffers 32
You can also checks the area that you defined inside the DTS by using:
cat /sys/kernel/debug/remoteproc/remoteproc0/carveout_memories
In my case:
Carveout memory entry:
Name: vdev0vring0
Virtual address: f8b4a303
DMA address: 0x10040000
Device address: 0x10040000
Length: 0x2000 Bytes
Carveout memory entry:
Name: vdev0vring1
Virtual address: 135e15b0
DMA address: 0x10042000
Device address: 0x10042000
Length: 0x2000 Bytes
Carveout memory entry:
Name: vdev0buffer
Virtual address: 00000000
DMA address: 0x00000000
Device address: 0x10044000
Length: 0x8000 Bytes
These two files are very helpful to debug and verify that everything is correct on your board.
Regards,
Kevin
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