I have a ISA frame grabber card with 2 MB of memory on it. This
memory is accesed through a one MB memory window at address 0xf00000.
A bit in a control register switches between the two memory banks.
No, what I would like to do is to mmap the frame grabber memory into a
user processes address space so that the user process sees it as two
MB of memory without having to do the bank switching manually.
Is it possible to do this? I have a vague memory of someone doing
something like this for GGI and an old bank switching VGA adapter.
It should be doable since it's essentially the same as a mmap of a
file, but I simply don't know enough about the MM layer do do this
myself.
I guess this is whatI want to do:
page_fault_handler(void *address)
{
if (address >= high_bank)
{
outb(0x01, bank_ctrl);
set_prot_flags(low_bank, 0x100000, PROT_NONE);
set_prot_flags(high_bank, 0x100000, PROT_READ | PROT_WRITE);
}
else
{
outb(0x00, bank_ctrl);
set_prot_flags(low_bank, 0x100000, PROT_READ | PROT_WRITE);
set_prot_flags(high_bank, 0x100000, PROT_NONE);
}
}
/Christer
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