On 2015-09-20 18:51, Ian Campbell wrote: > On Sat, 2015-09-19 at 18:49 +0200, Andreas Sundstrom wrote: >> Package: grub-xen-host >> Version: 2.02~beta2-22 >> Severity: important >> >> Dear Maintainer, >> >> Using 64-bit dom0 and 32-bit domU PV (para-virtualized) grub sometimes >> fail when chainloading the domU's grub. 64-bit domU seem to work 100% >> of the time. > Which grub are you starting with from dom0? > > If you want to boot a 32-bit guest (which includes chainloading a 32 > -bit grub) then you must start with the 32-bit grub-i386-xen.bin grub > binary to create a 32-bit guest. > > kexecing from 64-bit to 32-bit is not possible in the general case. In > fact I thought it was _impossible_ in all cases and would have ruled it > out as something you might be doing, except some of these registers > look like 64-bit values:
As you say it has not been possible at any time to use 64-bit grub from dom0 and then load either 32-bit grub or linux kernel from domU. I am using /usr/lib/grub-xen/grub-i386-xen.bin when I start my i386 domU's Thanks for your great blog entry about this by the way: https://blog.xenproject.org/2015/01/07/using-grub-2-as-a-bootloader-for-xen-pv-guests/ I have used it to get a better understanding of the whole process. >> (XEN) rax: 0000000000000000 rbx: 0000000000000000 rcx: > 0000000000000000 >> (XEN) rdx: 0000000000000000 rsi: 0000000000499000 rdi: 0000000000800000 >> (XEN) rbp: 000000000000000a rsp: 00000000005a5ff0 r8: 0000000000000000 >> (XEN) r9: 0000000000000000 r10: ffff83023e9b9000 r11: ffff83023e9b9000 >> (XEN) r12: 0000033f3d335bfb r13: ffff82d080300800 r14: ffff82d0802ea940 >> (XEN) r15: ffff83005e819000 cr0: 000000008005003b cr4: 00000000000506f0 >> (XEN) cr3: 0000000200b7a000 cr2: 0000000000000000 Well I don't know but I guess the XEN hypervisor is always running in 64-bit mode yes? I suppose that maybe even if the domU is 32-bit any errors showing up in "xl dmesg" reflects the mode that the hypervisor is run in? /Andreas
