libpciaccess MTRR splitting

Francisco Jerez currojerez at
Tue Feb 3 18:44:24 PST 2009


Since I switched to libpciaccess, I've been seeing errors like:

> error setting MTRR (base = 0x14200000, size = 0x00800000, type = 1) Invalid argument (22)

It's because the GPU I'm using (a siliconmotion SM720) has a register
area at the beginning of the PCI BAR which shouldn't be set to WC, and
the remaining memory (the actual framebuffer) isn't aligned at a size

I've been running a modified version of libpciaccess (diff attached)
that splits the memory range on properly aligned chunks before setting
the MTRRs.

If it turns out to be a reasonable approach, I'm willing to document
it more thoroughly and format it for git-am.

I've only implemented it for the linux_sysfs backend, but the logic at
pci_mapping_split is somewhat generic and another source file might be
better suited for it.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: mtrr_splitting.patch
Type: text/x-diff
Size: 5563 bytes
Desc: not available
URL: <>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 196 bytes
Desc: not available
URL: <>

More information about the xorg mailing list