[Xen-devel] Bugs in xl that affect stubdom+tapdisk2, and others

[John Weekes <lists.xen@xxxxxxxxxxxxxxxxxx>]

I'm having these problems when using "xl" in the latest c/s of 4.2 
(25912:651d965ee2c0):
- It's not allowing multiple domains to use the same images, at least 
under tapdisk2. If I start one domain using an image (a read-only CD-ROM 
image, for instance), then start another, I can see in "tap-ctl list" 
that only one of the domains actually receives the proper access. The 
other either never gets it, or it is disconnected after it's created -- 
I can't readily tell which.
- When I use "xl destroy" on a domain that also has an associated 
stubdom, "xl" tries to destroy the tapdisk2 entries for both the domain 
and its stubdomain, resulting in errors like these:
# xl destroy testvds4
libxl: error: libxl_blktap2.c:73:libxl__device_destroy_tapdisk: Unable 
to find type aio disk /servers/isos/DummyCD.iso: No such file or directory
libxl: error: libxl_blktap2.c:73:libxl__device_destroy_tapdisk: Unable 
to find type aio disk /servers/customers/testvds4.img: No such file or 
directory
libxl: error: libxl_blktap2.c:73:libxl__device_destroy_tapdisk: Unable 
to find type aio disk /servers/isos/DummyCD-2.iso: No such file or directory
libxl: error: libxl.c:1466:devices_destroy_cb: libxl__devices_destroy 
failed for 19
libxl: error: libxl.c:1466:devices_destroy_cb: libxl__devices_destroy 
failed for 18
If I'm reading the source correctly, it seems as though the various 
destruction functions aren't passing down the domid and ultimately 
libxl__device_destroy_tapdisk is calling tap_ctl_find, which just 
globally matches based on the type and name of the image, causing the 
errors on destroy. I was trying to find a quick fix, but it looks like 
any proper one will require querying xenstore for the tapdisk entries 
specific to the domain, and I'm not immediately able to make that 
change, so I've personally just switched back to using "xm" for the time 
being. (I don't know if this relates to the first bug re: multiple 
domains using the same image files).
Another, much more minor, bug in "xl" that I've found is that "xl 
uptime" will not run without an argument; it is supposed to just show 
all uptimes in this circumstance. This is an easy one-liner fix of 
modifying line:
tools/libxl/xl_cmdimpl.c:5749:    while ((opt = def_getopt(argc, argv, 
"s", "uptime", 1)) != -1) {
into this:

tools/libxl/xl_cmdimpl.c:5749:    while ((opt = def_getopt(argc, argv, 
"s", "uptime", 0)) != -1) {
Also, a couple of small typos in "xl" --

libxl.c:556:        LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "geting 
domain info list");
libxl.c:575:        LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "geting 
domain info list");
libxl.c:678:        LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "geting 
domain info list");
libxl.c:1393:        LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "non-existant 
domain %d", domid);
Also, running "xl sched-credit" always gives me an error, even though it 
seems to work. Maybe it should be silent if cpu pools aren't defined? 
Maybe it's supposed to be creating a second cpupool for the second CPU 
in this system, and isn't?
# xl sched-credit
libxl: error: libxl.c:596:cpupool_info: failed to get info for cpupool1
: No such file or directory
Cpupool Pool-0: tslice=5ms ratelimit=500us
Name                                ID Weight  Cap
Domain-0                             0  65535    0

As an additional note about 4.2 -- this isn't an "xl" issue, but rather 
a build problem -- even though I use "./configure --libdir=/usr/lib64", 
the build is still creating a "dist/install/usr/lib" directory, and 
because of this, running ./install.sh nukes my system's "/usr/lib" -> 
"/usr/lib64" softlink (which in turn causes all sorts of other problems 
until it's corrected). Files that are being put in that tree:
xen-4.2-testing.hg # find dist/install/usr/lib
dist/install/usr/lib
dist/install/usr/lib/xen
dist/install/usr/lib/xen/boot
dist/install/usr/lib/xen/boot/xenstore-stubdom.gz
dist/install/usr/lib/xen/boot/ioemu-stubdom.gz
dist/install/usr/lib/xen/boot/pv-grub-x86_64.gz
dist/install/usr/lib/xen/boot/hvmloader
dist/install/usr/lib/xen/boot/pv-grub-x86_32.gz
dist/install/usr/lib/xen/bin
dist/install/usr/lib/xen/bin/stubdom-dm
dist/install/usr/lib/xen/bin/qemu-io
dist/install/usr/lib/xen/bin/qemu-nbd
dist/install/usr/lib/xen/bin/qemu-img
dist/install/usr/lib/xen/bin/xenpaging
dist/install/usr/lib/xen/bin/qemu-dm
dist/install/usr/lib/xen/bin/qemu-system-i386
dist/install/usr/lib/xen/bin/qemu-ga
dist/install/usr/lib/xen/bin/stubdompath.sh

-John

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