On Fri, 2005-08-26 at 11:59 -0700, Linux Kernel Mailing List wrote: > tree d8b7aaaec93de93841b46e8e05a3b454d05bd357 > parent 26aad69e3dd854abe9028ca873fb40b410a39dd7 > author Linus Torvalds <[EMAIL PROTECTED]> Sat, 27 Aug 2005 00:49:22 -0700 > committer Linus Torvalds <[EMAIL PROTECTED]> Sat, 27 Aug 2005 00:49:22 -0700 > > Ignore disabled ROM resources at setup > > Writing even a disabled value seems to mess up some matrox graphics > cards. It may be a card-related issue, but we may also be writing > reserved low bits in the result. > > This was a fall-out of switching x86 over to the generic PCI resource > allocation code, and needs more debugging. In particular, the old x86 > code defaulted to not doing any resource allocations at all for ROM > resources. > > In the meantime, this has been reported to make X happier by Helge > Hafting <[EMAIL PROTECTED]>.
This "fix" also seems to break all powermac laptops around :( In fact, it might break any user of pci_map_rom() as it exposes a bug in that function. The problem is that their firmware doesn't assign a ROM resource as they have no ROM on the video chip (like most laptops). radeonfb and aty128fb among others will call pci_map_rom() to try to find an x86 BIOS ROM with some config tables in it. pci_map_rom "sees" that the resource is unassigned by testing the parent pointer, and calls pci_assign_resource() which, with this new patch, will do nothing. Unfortunately, pci_map_rom will not notice this failure, and will happily ioremap & access the bogus resource, thus causing the crash. I'll come up with a fix for pci_map_rom later today. While looking there, I also noticed pci_map_rom_copy() stuff and I'm surprised it was ever accepted in the tree. While I can understand that we might need to keep a cached copy of the ROM content (due to cards like matrox who can't enable both the ROM and the BARs among other issues), the whole idea of whacking a kernel virtual pointer in the struct resource->start of the ROM bar is just too disgusting for words and will probably cause "intersting" side effects in /proc, sysfs and others... Shouldn't we just have a pointer in pci_dev for the optional "ROM cache" instead ? Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
