>
> null pointer?
>
yep. See :
- Kernel/Core/FileSystem/Ext2FS.cs, line 23
- Kernel/Core/ADC/X86/FloppyDiskController.cs, lines 153-156
> Is this necessary? In any case, the kernel is actually loaded at the
> 1MB barrier, so we don't even touch this part of memory usually,
> especially not with the memory allocator.
I'm not a driver specialist but I try to write a DMA controller for SharpOS.
And I was wrong, it is not 1Mb but 32Mb (24 bits).
I just found a PDF (http://lwn.net/images/pdf/LDD3/ch15.pdf, page 31) that
exposes DMA buffers allocation constraints:
Most devices on modern buses can handle 32-bit addresses, meaning that
normal
memory allocations work just fine for them. Some PCI devices, however, fail
to
implement the full PCI standard and cannot work with 32-bit addresses. And
ISA
devices, of course, are limited to 24-bit addresses only.
Maybe it could be useful to add a parameter to the MemoryManager.Allocate()
method to indicate that we want a buffer in a specific memory region ?
Cedric
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