Messages in this thread | | | Subject | Re: PCI Express support for 2.4 kernel | From | Andi Kleen <> | Date | Mon, 15 Dec 2003 22:56:15 +0100 |
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Vladimir Kondratiev <vladimir.kondratiev@intel.com> writes: > > As alternative between 1 page and 256M, I see also lazy allocation on > per-bus basis: when bus is first accessed, ioremap 1Mb for it. On real > system, it is no more then 3-4 buses. This way, we will end with > several 1MB mappings. Finer granularity do not looks feasible, since > bus scanning procedure tries to access all devices.
For bus scanning fixmaps are fine, but for the normal use of the config space in the driver just doing ioremap once (e.g. at pci_enable_device time) and caching it is preferable. The number of PCI-E devices in a given system should be bounded, so e.g. when you have 100 devices you will only lose 400kB of vmalloc space this way which is quite reasonable.
I don't think dynamic fixmaps at each access would be a good idea.
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