Messages in this thread | | | From | Klaus Nielsen <> | Subject | Re: Unable to read memory mapped PCI memory the second time == freezeup.. | Date | Sat, 10 Jul 1999 17:11:06 +0200 |
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Mr. Garzik,
thank you for your suggestion. But unfortunately, as I mention in the previous post I have already tried readb() with the same result. Actually I think that they both results in a "movb" instruction on the Intel/x86 architecture.
Maybe it's a compatibility problem between the motherboard chipset and the PLX9052 PCI controller on the card.
It seems like the first read succeeds but leaves the card in a wrong state for subsequent reads. Well,- the subsequent reads actually seem to succeed. But when accessing the location in memory, to which data were moved from the PCI memory, with a conditional statement or for putting on a call stack - the system blocks. As if the memory are not yet ready to respond after the move operation.
I am puzzeled.
PS: The memory access flag in the card PCI COMMAND register is enabled. If not, it would have frozen on the actual 'movb' instruction that attempted to read from the card memory. And the first one at that.
On Sat, 10 Jul 1999, Jeff Garzik wrote: > Read linux/Documentation/IO-mapping.txt, and then use read?() and > write?() for MMIO. For example: > > byArgh = readb(global_vmemaddr); > if(byArgh==0) printk(KERN_DEBUG "byArgh\n"); > writeb (0x5a, global_vmemaddr); > byArgh = readb(global_vmemaddr);
-- Best regards, Klaus. ---------------------------------------------------- Klaus J. O. Nielsen System Engineer, COCOM A/S, www.cocom.dk Personal web: http://www.zorland.dk/jimbo PGP public key: http://www.zorland.dk/jimbo/kjn.asc
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