Re: xenstore utils dropped support for -s in 4.15

[Juergen Gross <jgross@suse.com>]

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On 11.04.21 00:02, Henrik Riomar wrote:
> Hi,
> 
> In Alpine and Debian (probably elsewhere as well), the -s flag removed in these two commits:
>   * https://github.com/xen-project/xen/commit/fa06cb8c38832aafe597d719040ba1d216e367b8
>   * https://github.com/xen-project/xen/commit/c65687ed16d2289ec91036ec2862a4b4bd34ea4f
> is actually used in the init scripts.
> 
> On one of the systems I tested 4.15 on things just hangs due to this:
> 2222  open("/lib/libxentoolcore.so.1", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = -1 ENOENT (No such file or directory)
> 2222  open("/usr/local/lib/libxentoolcore.so.1", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = -1 ENOENT (No such file or directory)
> 2222  open("/usr/lib/libxentoolcore.so.1", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 3
> 2222  fcntl(3, F_SETFD, FD_CLOEXEC)     = 0
> 2222  fstat(3, {st_mode=S_IFREG|0755, st_size=14072, ...}) = 0
> 2222  read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240\20\0\0\0\0\0\0"..., 960) = 960
> 2222  mmap(NULL, 20480, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f9925c02000
> 2222  mmap(0x7f9925c03000, 4096, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED, 3, 0x1000) = 0x7f9925c03000
> 2222  mmap(0x7f9925c04000, 4096, PROT_READ, MAP_PRIVATE|MAP_FIXED, 3, 0x2000) = 0x7f9925c04000
> 2222  mmap(0x7f9925c05000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x2000) = 0x7f9925c05000
> 2222  close(3)                          = 0
> 2222  mprotect(0x7f9925c0f000, 4096, PROT_READ) = 0
> 2222  mprotect(0x7f9925ca6000, 4096, PROT_READ) = 0
> 2222  mprotect(0x7f9925c05000, 4096, PROT_READ) = 0
> 2222  mprotect(0x5601e65dc000, 4096, PROT_READ) = 0
> 2222  stat("/var/run/xenstored/socket", 0x7ffd95b9f080) = -1 ENOENT (No such file or directory)
> 2222  access("/dev/xen/xenbus", F_OK)   = 0
> 2222  stat("/dev/xen/xenbus", {st_mode=S_IFCHR|0600, st_rdev=makedev(0xa, 0x3e), ...}) = 0
> 2222  open("/dev/xen/xenbus", O_RDWR|O_LARGEFILE) = 3
> 2222  rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7f9925c59c4b}, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
> 2222  write(3, "\2\0\0\0\0\0\0\0\0\0\0\0\2\0\0\0", 16) = 16
> 2222  write(3, "/\0", 2)                = 2
> 2222  read(3,
> 
> Reverting the two commits mentioned above restores a booting system.
> 
> The -s flag was introduced in 2005 or so, so I guess you can say that dropping it should
> at least be mentioned in the release notices, and an alternative be described, or
> -s functionally should be brought back.

The -s served exactly no purpose.

It was meant to force socket usage. A socket will be used anyway in
case xenstored is running in dom0, so specifying -s won't change
anything in this case. In case xenstored is running in a stubdom
specifying -s will result in the utility NOT working, as there is
no socket connection to xenstored available.


Juergen

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