Xen devel - May 2006 - MMAP failure after creating an HVM guest

In tracking down an X windows problem I''ve discovered that an
`mmap'' on
Dom0 fails after an HVM guest is created.  The problem is with the 2
system calls:

	fd = open("/dev/mem", O_RDWR);
	p = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);

These calls work fine until after the first HVM guest is created and
then the `mmap'' fails with an EFAULT.  Interestingly enough, the
`mmap''
works if `/dev/mem'' is opened read only and the failure only happens
after the HVM guest goes into protected mode, if you destroy an HVM
Linux guest while it''s still in Grub then this `mmap'' will
still work.

--
Don Dugger
"Censeo Toto nos in Kansa esse decisse." - D. Gale
Donald.D.Dugger@intel.com
Ph: (303)440-1368


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