Hi, I'm not sure whether my comments can help you or not.
I also asked a similar question to the community. The related articles are as follows: http://sourceforge.net/p/genode/mailman/message/34341641/ I modified my source code referring to the above link. Based on the answers from the community, I used the "dma_alloc_coherent()" as follows in the device driver in the Normal World: /* variables for buffer */ static dma_addr_t genblk_buf_phys; static void * genblk_buf *genblk_buf* = dma_alloc_coherent(NULL, 1024, *&genblk_buf_phys*, GFP_KERNEL); /* send smc instruction to initialize buffer */ smc_blk(instruction_id, *genblk_buf_phys*, 1024); In the Secure World, tz_vmm was modified to handle this as follows: /* variables for buffer */ void * _buf; Genode::size_t _buf_size; addr_t buf_base; addr_t buf_top, ram_top, buf_off; Ram * ram; bool buf_err; buf_base = (addr_t)_vm->state()->r1; _buf_size = (Genode::size_t)_vm->state()->r2; buf_top = buf_base + _buf_size; ram = _vm->ram(); ram_top = ram->base() + ram->size(); buf_err = buf_top <= buf_base; buf_err |= buf_base < ram->base(); buf_err |= buf_top >= ram_top; if (buf_err) { PERR("blk: illegal buffer constraints"); break; } buf_off = buf_base - ram->base(); *_buf* = (void *)(ram->local() + buf_off); After this, *_buf* is used to refer the shared buffer in the Secure World, and *genblk_buf* is used in the Normal World. I hope my humble comments can help you. Jaemin Park. On Thu, Dec 10, 2015 at 1:15 AM, Stefan Brenner <bren...@ibr.cs.tu-bs.de> wrote: > Hi, > > currently we're working with the TrustZone VMM example from Genode based > on Genode 15.05 on i.MX53 QSB. > > We have a shared buffer in normal world, which we want to use for > cross-world communication. > > Currently the buffer is allocated using mmap MAP_SHARED | MAP_ANON. > > We're having strange issues/problems/inconsistencies when accessing the > memory range in Genode (secure world) after normal world has written to it. > > We read that uncached memory should be used for this, or the cache lines > have to be flushed/invalidated. However, apparently we can't get either > of these options working. > > So our questions as follows: > > 1) We use mmap(NULL, <size>, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANON, > -1, 0) to allocate the buffer in normal world (Linux). Is there a better > way to allocate uncached memory? > > 2) We've tried __cpuc_flush_user_all(), __cpuc_flush_kern_all() in order > to invalidate all cache lines (later maybe only the affected cache lines > once this works in general). Is this correct, to do this in normal world > (i.e. Linux)? > > 3) At the moment we assume that Genode doesn't have to invalidate/flush > its cache lines because as it is the VMM it should be aware of the fact > that the cache might be stale. > > Any help is appreciated. A short hint: Currently our idea is to send an > hypercall to the Genode VMM after Linux has written to the buffer, so > Genode will pretty quickly access the memory after it has been written > to from Linux. > > Best regards, Stefan. > > -- > M.Sc. Stefan Brenner > Institute of Operating Systems and Computer Networks > Distributed Systems Group > TU Braunschweig > > www: https://www.ibr.cs.tu-bs.de/users/brenner > mail: bren...@ibr.cs.tu-bs.de > > > ------------------------------------------------------------------------------ > _______________________________________________ > genode-main mailing list > genode-main@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/genode-main >
------------------------------------------------------------------------------
_______________________________________________ genode-main mailing list genode-main@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/genode-main
