Linux/PROCESSOR-SDK-AM335X: Loadable module address mapping

Hi Tim,

Do you use AM335x PSDK Linux? If yes, which version? The latest version is 5.03 (kernel v4.14.79), available at below link.

Regards,
Pavel

Tim,

To translate physical address to virtual, you’ll need to map the physically memory to virtual memory using linux kernal ioremap system call. In example, see below e2e threads:

Regarding virtual to physical address translation, you can explore virt_to_phys() and/or gen_pool_virt_to_phys() functions.

linux-4.14.79/Documentation/bus-virt-phys-mapping.txt

linux-4.14.79/lib/test_debug_virtual.c

linux-4.14.79/lib/genalloc.c

Regards,
Pavel

We are using an older version of the TI SDK, SDK 7.  Kernel version 3.12.10.

Tim,

The pointers that I have provided in my second post, should be also applicable for SDK 7 (kernel v3.12.10)

Regards,
Pavek

the gen_pool_virt_to_phys() looks interesting.  Any thoughts on where I get the gen_pool for the loadable modules?

We have a loadable module we wrote that is not playing nice and occasionally causes some kernel panics. 

[506944.244718] PC is at 0xbdd13e70
[506944.248498] LR is at apmTimerCallback+0x1d8/0x3e0 [apm]
[506944.254701] pc : [<bdd13e70>]    lr : [<bf2693b8>]    psr: 200e0093
[506944.254701] sp : cd085e10  ip : c0023028  fp : cd085e5c
[506944.268301] r10: 00000000  r9 : c07d6064  r8 : cd085e2c

We would like to try and see where this PC register is pointing, but it gives us the loadable module virtual address ( bdd13e70 ) and I would really like to get that into the kalloc virtual equivalent ( 0xC0000000 - 0xD0000000 since we have 256 MB RAM ).

Tim Potter said:

the gen_pool_virt_to_phys() looks interesting.  Any thoughts on where I get the gen_pool for the loadable modules?

gen_pool C and H files are located at:

linux-kernel/lib/genalloc.c

linux-kernel/include/linux/genalloc.h

You should be able to use these files in your kernel loadable module.

For example of gen_pool usage, refer to below kernel files:

linux-kernel/drivers/soc/ti/pm33xx.c

linux-kernel/drivers/net/ethernet/ti/prueth.c

linux-kernel/drivers/memory/ti-emif-pm.c

Regards,
Pavel