On 2011-05-25 10:13, Ian Campbell wrote: > On Tue, 2011-05-24 at 18:18 +0200, Jan Kiszka wrote: >> On 2011-05-24 18:06, Ian Campbell wrote: >>> On Sun, 2011-05-22 at 13:00 +0200, Jan Kiszka wrote: >>>> From: Jan Kiszka <jan.kis...@siemens.com> >>>> >>>> -machine somehow suggests that it selects the machine, but it doesn't. >>>> Fix that before this command is set in stone. >>>> >>>> Actually, -machine should supersede -M and allow to introduce arbitrary >>>> per-machine options to the command line. That will change the internal >>>> realization again, but we will be able to keep the user interface >>>> stable. >>>> >>>> CC: Anthony PERARD <anthony.per...@citrix.com> >>>> Signed-off-by: Jan Kiszka <jan.kis...@siemens.com> >>> >>> "-machine xenfv" doesn't work for me with this patch, it gives: >>> Program received signal SIGSEGV, Segmentation fault. >>> hypercall_buffer_cache_lock (xch=0x0) at xc_hcall_buf.c:36 >>> 36 xc_hcall_buf.c: No such file or directory. >>> in xc_hcall_buf.c >>> (gdb) bt >>> #0 hypercall_buffer_cache_lock (xch=0x0) at xc_hcall_buf.c:36 >>> #1 0xb7d53f1d in hypercall_buffer_cache_alloc (xch=0x0, >>> b=0xbffff77c, nr_pages=1) at xc_hcall_buf.c:52 >>> #2 xc__hypercall_buffer_alloc_pages (xch=0x0, b=0xbffff77c, >>> nr_pages=1) at xc_hcall_buf.c:128 >>> #3 0xb7d54028 in xc__hypercall_buffer_alloc (xch=0x0, >>> b=0xbffff77c, size=16) at xc_hcall_buf.c:162 >>> #4 0xb7d42719 in xc_get_hvm_param (handle=0x0, dom=248, param=5, >>> value=0xbffff810) at xc_domain.c:1078 >>> #5 0x08252777 in xen_hvm_init () at >>> /home/ianc/devel/qemu.git/xen-all.c:803 >>> #6 0x082921e9 in pc_xen_hvm_init (ram_size=536870912, >>> boot_device=0xbffffabb "cda", kernel_filename=0x0, kernel_cmdline=0x82d648f >>> "", initrd_filename=0x0, cpu_model=0x0) at >>> /home/ianc/devel/qemu.git/hw/pc_piix.c:246 >>> #7 0x081e3f0e in main (argc=26, argv=0xbffffba4, envp=0xbffffc10) >>> at /home/ianc/devel/qemu.git/vl.c:3162 >>> >>> I suspect this is because xen_init() (which sets xch) is never called, >>> perhaps because it causes the accelerator to always be tcg? If I use >>> "-machine xenfv,accel=xen" then it works as expected, -M continues to >>> work too AFAICT. >>> >>> It would be nice to retain the behaviour of defaulting to accel=xen for >>> machine=xenfv. (to be honest I can't quite see where this behaviour came >>> from, nor what about this patch changes it...) >> >> Well, first of all I think this revealed a Xen bug because it crashes >> when you try to run xenfv with an inappropriate accelerator, no? What is >> the result of -machine xenfv,accel=tcg or, without my patch, -M xenfv >> -machine accel=tcg? > > Unsurprisingly it crashed... > > I'm not sure if this is a bug in the xen side of simply a case of > providing enough rope. I didn't really follow the threads which resulted > in the accel stuff all that closely so I'm not sure what the intention > was, it seems to me that the accel option is invalid with certain > machine types though. > > I suppose in theory -machine xenpv,accel=kvm might result in xenner or > something, accel=xenpv,tcg I'm less sure about (perhaps xenner too?). > For -machine xenfv I don't expect anything other than accel=xen makes > much sense.
The point is that crashing is always a very poor way of reporting a misconfiguration to the user. I bet you are able to detect and report that more gracefully, e.g. during xenfv machine init. > >> Then the question is what accel options are actually picked with >> -machine xenfv, or why the default options are maybe not considered. I >> don't have any Xen around, but I will check how far I can debug this - >> or actually try to understand what I coded if nothing helps. > > I saw a follow up patch -- I'll give it a go. TIA, Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux
