Messages in this thread |  | | Date | Thu, 4 Oct 2001 10:58:33 +0200 (CEST) | From | Etienne Lorrain <> | Subject | specific optimizations for unaccelerated framebuffers |
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Just a question:
Has anybody ever tried to have a copy of the video memory in the main memory. All the software would access the copy in main memory, and the standart DMA is used (permanently) to update the real video memory. Maybe a 32 bit int could be used to skip unmodified 64K pages (1 bit per page). The main processor would never have to wait for PCI read/writes.
In fact the question is: what kind of bandwidth can we have from a standart PC DMA (memory to memory copy)? The other problem could be the addresses limits, but using the VESA1 interface (window switching at 0xA0000), the video memory image below 16 Mb and known I/O ports (see Gujin) would solve that.
Someone has bandwidth measures? Etienne.
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