Re: [Bug #12608] 2.6.29-rc powerpc G5 Xorg legacy_mem regression

Jesse Barnes
2009-02-06T22:45:10Z

On Friday, February 6, 2009 2:17 pm Hugh Dickins wrote:
> On Fri, 6 Feb 2009, Jesse Barnes wrote:
> > Hugh, did you get a chance to try my X patch (w/o Ben's patch applied)?
> > If it also works, we should apply it to X too, if only to make porting to
> > future platforms a little easier.
>
> I have tried it now: I'm sorry to say it does not work, fails with
> (WW) xf86MapDomainMem(): mmap() failure: No such device or address
>
> Fatal server error:
> AddScreen/ScreenInit failed for driver 0
>
> The "mmap() failure" line is of course the one you're intentionally
> showing, but the AddScreen/ScreenInit one is not what you want.
> Presumably it demands something other than a NULL addr returned,
> but I haven't followed that up at all.
>
> I have tried the obvious patch below, which reverts to the original
> code if the mmap fails: this works, but presumably negates much of
> what you intended to achieve with legacy_mem.
>
> Easy for me to try something else, fire away.
>
> Hugh
>
> --- a/hw/xfree86/os-support/bus/linuxPci.c
> +++ b/hw/xfree86/os-support/bus/linuxPci.c
> @@ -501,8 +501,10 @@ xf86MapDomainMemory(int ScreenNum, int F
> if (fd >= 0)
> close(fd);
> if (addr == NULL || addr == MAP_FAILED) {
> - perror("mmap failure");
> - FatalError("xf86MapDomainMem(): mmap() failure\n");
> + xf86Msg(X_WARNING, "xf86MapDomainMem(): mmap() failure: %s\n",
> + strerror(errno));
> + return linuxMapPci(ScreenNum, Flags, dev, Base, Size,
> + PCIIOC_MMAP_IS_MEM);
> }
> return addr;
> }

Yeah that should work. I always hated this code (well most of X actually); we
could probably clean up the logic a little. If this works I'll send it
out to the Xorg list for review.

--
Jesse Barnes, Intel Open Source Technology Center

diff --git a/hw/xfree86/os-support/bus/linuxPci.c b/hw/xfree86/os-support/bus/linuxPci.c
index 263fd8f..fa0fc0a 100644
--- a/hw/xfree86/os-support/bus/linuxPci.c
+++ b/hw/xfree86/os-support/bus/linuxPci.c
@@ -471,23 +471,18 @@ xf86MapDomainMemory(int ScreenNum, int Flags, struct pci_device *dev,
int fd = -1;
pointer addr;

- /*
- * We use /proc/bus/pci on non-legacy addresses or if the Linux sysfs
- * legacy_mem interface is unavailable.
- */
- if ((Base > 1024*1024) || ((fd = linuxOpenLegacy(dev, "legacy_mem")) < 0))
- return linuxMapPci(ScreenNum, Flags, dev, Base, Size,
- PCIIOC_MMAP_IS_MEM);
- else
- addr = mmap(NULL, Size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, Base);
-
- if (fd >= 0)
- close(fd);
- if (addr == NULL || addr == MAP_FAILED) {
- perror("mmap failure");
- FatalError("xf86MapDomainMem(): mmap() failure\n");
+ if (Base <= 1024*1024) {
+ /* Try legacy_mem (may not be available or implemented) */
+ if ((fd = linuxOpenLegacy(dev, "legacy_mem")) < 0) {
+ addr = mmap(NULL, Size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, Base);
+ close(fd);
+ if (addr && addr != MAP_FAILED)
+ return addr;
+ }
}
- return addr;
+
+ /* Fall back to old method if legacy_mem fails or Base >= 1M */
+ return linuxMapPci(ScreenNum, Flags, dev, Base, Size, PCIIOC_MMAP_IS_MEM);
}

/**