Messages in this thread | | | Date | 4 Mar 1999 16:26:47 -0000 | From | Christer Weinigel <> | Subject | Automatic bank switching for a frame grabber? |
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Hi,
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
-- If it's tourist season, why can't we shoot them?
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