[libvirt] bhyve: grub-bhyve: support overriding just --root flag

Hi, I was trying to get a GPT-formatted VM boot on FreeBSD using the bhyve driver and the grub-bhyve bootloader. Turns out that libvirt 3.9.0 hardcodes the boot partition to (hd0,msdos1) or allows overriding it completly using <bootloader_args>. I hacked together a patch that allows overring just the --root argument to grub-bhyve and updated the documentation: https://github.com/problame/libvirt/commit/5fd1265c05987d907d9f1d9913dbee... Obviously, this does not meet quality standards and should not be merged as is, but maybe spawn some discussion (if anyone is actually using bhyve + libvirt). Cheers, Christian --- commit 5fd1265c05987d907d9f1d9913dbee832a227889 Author: Christian Schwarz <me(a)cschwarz.com&gt; Date: Sat Nov 11 16:15:05 2017 +0100 bhyve: grub-bhyve: support overriding just the --root argument in domain config diff --git a/docs/drvbhyve.html.in b/docs/drvbhyve.html.in index 63260afae..2583bfa01 100644 --- a/docs/drvbhyve.html.in +++ b/docs/drvbhyve.html.in @@ -300,17 +300,26 @@ are omitted, libvirt will try and infer boot ordering from user-supplied &lt;boot order='N'&gt; configuration in the domain. Failing that, it will boot the first disk in the domain (either <code>cdrom</code>- or <code>disk</code>-type devices). If the disk type is <code>disk</code>, it will -attempt to boot from the first partition in the disk image.</p> +attempt to boot from the first partition in the disk image, assuming +an <code>msdos</code> partitioning scheme +(i.e. <code>grub-bhyve --root hd0,msdos1</code>). +You can override this behavior using <code>bootloader_args</code> or <code>bootloader_grub_root</code>. +</p> <pre> ... &lt;bootloader&gt;/usr/local/sbin/grub-bhyve&lt;/bootloader&gt; +&lt;!-- the following tag overrides all args to grub-bhyve --&gt; &lt;bootloader_args&gt;...&lt;/bootloader_args&gt; +&lt;!-- the following tag overrides just the --root argument to grub-bhyve --&gt; +&lt;bootloader_grub_root&gt;hd0,gpt1&lt;/bootloader_grub_root&gt; ... </pre> -<p>Caveat: <code>bootloader_args</code> does not support any quoting. -Filenames, etc, must not have spaces or they will be tokenized incorrectly.</p> +<p>Caveats when using <code>bootloader_args</code>: it does not support any quoting. +Filenames, etc, must not have spaces or they will be tokenized incorrectly. +Additionally, you will have to maintain your own <code>--device-map</code> +file and keep it in sync with the domain XML.</p> <h3><a id="uefi">Using UEFI bootrom, VNC, and USB tablet</a></h3> diff --git a/src/bhyve/bhyve_command.c b/src/bhyve/bhyve_command.c index 55032ae1d..6cab6e516 100644 --- a/src/bhyve/bhyve_command.c +++ b/src/bhyve/bhyve_command.c @@ -774,15 +774,21 @@ virBhyveProcessBuildGrubbhyveCmd(virDomainDefPtr def, } virCommandAddArg(cmd, "--root"); - if (userdef != NULL) { - if (userdef->device == VIR_DOMAIN_DISK_DEVICE_CDROM) + if (def->os.bootloaderGrubRoot != NULL) { + virCommandAddArg(cmd, def->os.bootloaderGrubRoot); + } else { + + if (userdef != NULL) { + if (userdef->device == VIR_DOMAIN_DISK_DEVICE_CDROM) + virCommandAddArg(cmd, "cd"); + else + virCommandAddArg(cmd, "hd0,msdos1"); + } else if (cd != NULL) { virCommandAddArg(cmd, "cd"); - else + } else { virCommandAddArg(cmd, "hd0,msdos1"); - } else if (cd != NULL) { - virCommandAddArg(cmd, "cd"); - } else { - virCommandAddArg(cmd, "hd0,msdos1"); + } + } virCommandAddArg(cmd, "--device-map"); diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 7dfd7b54e..ecd1f71dd 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -18141,6 +18141,7 @@ virDomainDefParseXML(xmlDocPtr xml, def->os.bootloader = virXPathString("string(./bootloader)", ctxt); def->os.bootloaderArgs = virXPathString("string(./bootloader_args)", ctxt); + def->os.bootloaderGrubRoot = virXPathString("string(./bootloader_grub_root)", ctxt); tmp = virXPathString("string(./os/type[1])", ctxt); if (!tmp) { diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h index e3f060b12..f969e9195 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -1884,6 +1884,7 @@ struct _virDomainOSDef { char *slic_table; virDomainLoaderDefPtr loader; char *bootloader; + char *bootloaderGrubRoot; char *bootloaderArgs; int smbios_mode;