When booting xen hypervisor e.g. with vga=794 or vga=0x31a it falls back to ask for the mode without any "mode-failed" output. When I select the mode manually in the ask prompt it works fine. Reproducible: Always Steps to Reproduce: 1. install xen hypervisor with dom0 kernel 2. add e.g. vga=794 to kernel line in menu.lst 3. boot xen hypervisor with dom0 kernel Actual Results: ask prompt/dialog as if you added vga=ask parameter Expected Results: switch to vga mode in e.g. 1280x1024x16 or any output that the selected mode is not supported /boot/grub/menu.lst excerpt: ------------------------------------------------- title=Gentoo Linux Xen - 2.6.18-r12 root (hd0,0) kernel /xen.gz cpufreq=dom0-kernel vga=794 module /vmlinuz-2.6.18-r12-fb-xen0 root=/dev/sda3 Portage 2.1.4.5 (default/linux/x86/2008.0/desktop, gcc-4.1.2, glibc-2.6.1-r0, 2.6.18-xen-r12 i686) ================================================================= System uname: 2.6.18-xen-r12 i686 AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ Timestamp of tree: Sat, 15 Nov 2008 11:00:14 +0000 ccache version 2.4 [enabled] app-shells/bash: 3.2_p33 dev-lang/python: 2.4.4-r13, 2.5.2-r7 dev-util/ccache: 2.4-r7 sys-apps/baselayout: 1.12.11.1 sys-apps/sandbox: 1.2.18.1-r2 sys-devel/autoconf: 2.61-r2 sys-devel/automake: 1.9.6-r2, 1.10.1-r1 sys-devel/binutils: 2.18-r3 sys-devel/gcc-config: 1.4.0-r4 sys-devel/libtool: 1.5.26 virtual/os-headers: 2.6.23-r3 ACCEPT_KEYWORDS="x86" CBUILD="i686-pc-linux-gnu" CFLAGS="-O2 -march=i686 -pipe -mno-tls-direct-seg-refs" CHOST="i686-pc-linux-gnu" CONFIG_PROTECT="/etc" CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/env.d /etc/gconf /etc/terminfo /etc/udev/rules.d" CXXFLAGS="-O2 -march=i686 -pipe" DISTDIR="/usr/portage/distfiles" FEATURES="ccache distlocks metadata-transfer parallel-fetch sandbox sfperms strict unmerge-orphans userfetch" GENTOO_MIRRORS="http://distfiles.gentoo.org http://distro.ibiblio.org/pub/linux/distributions/gentoo" LDFLAGS="-Wl,-O1" MAKEOPTS="-j4" PKGDIR="/usr/portage/packages" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --stats --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages" PORTAGE_TMPDIR="/var/tmp" PORTDIR="/usr/portage" SYNC="rsync://rsync.gentoo.org/gentoo-portage" USE="X acl acpi alsa berkdb bluetooth branding bzip2 cairo cdr cli cracklib crypt cups dbus dri dvd dvdr dvdread eds emboss encode esd evo fam firefox fortran gdbm gif gnome gpm gstreamer gtk hal hvm iconv ipv6 isdnlog jpeg kde ldap libnotify mad midi mikmod mp3 mpeg mudflap ncurses nls nptl nptlonly ntplonly ogg opengl openmp pam pcre pdf perl png ppds pppd python qt3 qt3support qt4 quicktime readline reflection sdl session spell spl ssl startup-notification svg sysfs tcpd tiff truetype unicode usb vorbis win32codecs x86 xml xorg xv zlib" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1 emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mmap_emul mulaw multi null plug rate route share shm softvol" APACHE2_MODULES="actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" ELIBC="glibc" INPUT_DEVICES="keyboard mouse evdev" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" USERLAND="GNU" VIDEO_CARDS="fbdev glint i810 intel mach64 mga neomagic nv r128 radeon savage sis tdfx trident vesa vga via vmware voodoo" Unset: CPPFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, FFLAGS, INSTALL_MASK, LANG, LC_ALL, LINGUAS, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS, PORTDIR_OVERLAY
Sry, thought this is a gentoo specific problem because this worked on a Ubuntu Server with a similar configuration. The Xen hypervisor does expect a different syntax. For me vga=mode-0x031a is the solution. You can read more about this here: http://lists.xensource.com/archives/html/xen-changelog/2007-06/msg00206.html
