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fw_cfg: Adopt /opt/RFQDN convention

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FW CFG's primary user is QEMU, which uses it to expose configuration
information (in the widest sense) to Firmware.  Thus the name FW CFG.

FW CFG can also be used by others for their own purposes.  QEMU is
merely acting as transport then.  Names starting with opt/ are
reserved for such uses.  There is no provision, however, to guide safe
sharing among different such users.

Fix that, loosely following QMP precedence: names should start with
opt/RFQDN/, where RFQDN is a reverse fully qualified domain name you
control.

Based on a more ambitious patch from Michael Tsirkin.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Gabriel L. Somlo <somlo@cmu.edu>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Gabriel Somlo <somlo@cmu.edu>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Markus Armbruster 2016-04-18 18:29:50 +02:00
parent ef5d5641f5
commit 63d3145aad
2 changed files with 36 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
docs/specs/fw_cfg.txt
View File

@ -210,29 +210,27 @@ the following syntax:
-fw_cfg [name=]<item_name>,file=<path>
where <item_name> is the fw_cfg item name, and <path> is the location
on the host file system of a file containing the data to be inserted.
Small enough items may be provided directly as strings on the command
line, using the syntax:
Or
-fw_cfg [name=]<item_name>,string=<string>
The terminating NUL character of the content <string> will NOT be
included as part of the fw_cfg item data, which is consistent with
the absence of a NUL terminator for items inserted via the file option.
See QEMU man page for more documentation.
Both <item_name> and, if applicable, the content <string> are passed
through by QEMU without any interpretation, expansion, or further
processing. Any such processing (potentially performed e.g., by the shell)
is outside of QEMU's responsibility; as such, using plain ASCII characters
is recommended.
Using item_name with plain ASCII characters only is recommended.
NOTE: Users *SHOULD* choose item names beginning with the prefix "opt/"
when using the "-fw_cfg" command line option, to avoid conflicting with
item names used internally by QEMU. For instance:
Item names beginning with "opt/" are reserved for users. QEMU will
never create entries with such names unless explicitly ordered by the
user.
-fw_cfg name=opt/my_item_name,file=./my_blob.bin
To avoid clashes among different users, it is strongly recommended
that you use names beginning with opt/RFQDN/, where RFQDN is a reverse
fully qualified domain name you control. For instance, if SeaBIOS
wanted to define additional names, the prefix "opt/org.seabios/" would
be appropriate.
Similarly, QEMU developers *SHOULD NOT* use item names prefixed with
"opt/" when inserting items programmatically, e.g. via fw_cfg_add_file().
For historical reasons, "opt/ovmf/" is reserved for OVMF firmware.
Prefix "opt/org.qemu/" is reserved for QEMU itself.
Use of names not beginning with "opt/" is potentially dangerous and
entirely unsupported. QEMU will warn if you try.

24
qemu-options.hx
View File

@ -2864,18 +2864,32 @@ ETEXI
DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
"-fw_cfg [name=]<name>,file=<file>\n"
" add named fw_cfg entry from file\n"
" add named fw_cfg entry with contents from file\n"
"-fw_cfg [name=]<name>,string=<str>\n"
" add named fw_cfg entry from string\n",
" add named fw_cfg entry with contents from string\n",
QEMU_ARCH_ALL)
STEXI
@item -fw_cfg [name=]@var{name},file=@var{file}
@findex -fw_cfg
Add named fw_cfg entry from file. @var{name} determines the name of
the entry in the fw_cfg file directory exposed to the guest.
Add named fw_cfg entry with contents from file @var{file}.
@item -fw_cfg [name=]@var{name},string=@var{str}
Add named fw_cfg entry from string.
Add named fw_cfg entry with contents from string @var{str}.
The terminating NUL character of the contents of @var{str} will not be
included as part of the fw_cfg item data. To insert contents with
embedded NUL characters, you have to use the @var{file} parameter.
The fw_cfg entries are passed by QEMU through to the guest.
Example:
@example
-fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin
@end example
creates an fw_cfg entry named opt/com.mycompany/blob with contents
from ./my_blob.bin.
ETEXI
DEF("serial", HAS_ARG, QEMU_OPTION_serial, \