Oh man, sorry, those damn keyboard shortcuts, let me try again :-)
I wonder if anyone can help with some hints in this situation:
here is a code fragment to illustrate the questions:
if ((ai = kmalloc(sizeof(alloc_info_t) + 4 * szw, GFP_ATOMIC |
GFP_DMA)) != NULL) {
ai->src = FROM_KMALLOC;
printk("\n%s:%d %p\n", __FUNCTION__, __LINE__, ai);
basically, a block of contiguous memory is allocated. This block is
needed to set up some DMA descriptors, so it needs to be uncached, and
I thought this is what GFP_DMA flag is for.
I stop execution using a JTAG probe right after the printk above, and
examine the TLB matching the allocated address.
This is what printk reports:
sal_alloc:163 eee76000
And the TLB record for this memory is the default kernel 256M page:
61 : 00 e0000000 256MB V0 -> 0_20000000 U:0000 ---G- ---XWR
Which is obviously cached (missing the I bit set).
How is this supposed to work?
Is this right to expect the address returned by kmalloc() to be mapped
to uncached TLB in case GFP_DMA flag is passed in?
What are the proper ways of setting up shared memory in this kernel?
Any hints will be highly appreciated,
TIA,
Vadim
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