Bug 19026

Summary:	pci-sysfs resourceN files are not available on all architectures
Product:	xorg	Reporter:	Matt Turner <mattst88>
Component:	Lib/pciaccess	Assignee:	Xorg Project Team <xorg-team>
Status:	RESOLVED WORKSFORME	QA Contact:	Xorg Project Team <xorg-team>
Severity:	major
Priority:	high	CC:	armin76, diskman, idr, jeremyhu, pva, remi
Version:	unspecified
Hardware:	All
OS:	All
URL:	http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=485528
Whiteboard:	2011BRB_Reviewed
i915 platform:		i915 features:

Description Matt Turner 2008-12-11 12:28:33 UTC

This bug was filed by Julien Cristau at the Debian Bug Tracking system but never seemed to make it to fd.o's bugzilla.

> the pci_device_map_range() function from libpciaccess which is used by
> the X drivers to map pci BARs is implemented on linux using sysfs
> resourceN files, which the kernel only creates on architectures where
> HAVE_PCI_MMAP is defined.  This is not the case for alpha, parisc, mips
> and m68k, as far as I can tell.  See pci_create_resource_files() in
> linux/drivers/pci/pci-sysfs.c, and the respective include/asm-*/pci.h
> headers.
>
> This means that future versions of X (starting with xorg-server 1.5) are
> not going to work on these architectures unless this is fixed.  We need
> to either get the kernel fixed, or fall back to mmaping /dev/mem in
> libpciaccess.

Is it really acceptable to switch to libpciaccess and provide no fallback for these platforms?

Ideally, the solution is that each platform implement sysfs-pci resource in the kernel, but in the real world, you file a bug detailing the ideal situation and it rots for 6 months (http://bugzilla.kernel.org/show_bug.cgi?id=10893). Even if that were fixed tomorrow, at least PA-RISC, MIPS, and M68K systems are still left in the cold. I believe the BSDs have also run into problems with this.

Please implement a fallback in libpciaccess (directly access /dev/mem or similar).

By implementing even a temporary fallback (until all the kernel implementations are finished), it appears that the following bugs (symptoms of this problem) would be instantly fixed.

bug 16549, bug 15521, bug 17801.

Comment 1 Rémi Cardona 2009-04-01 08:49:32 UTC

Ping, any updates here?

Comment 2 Jeremy Huddleston Sequoia 2011-10-16 16:33:25 UTC

Is pci_device_linux_sysfs_map_legacy sufficient for the needs of drivers to 
fallback on /dev/mem?

Comment 3 Matt Turner 2017-03-13 19:45:35 UTC

Alpha was fixed long ago. No one else seems to care (or their platforms have been fixed too)

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