On Thu, 2011-11-10 at 10:55 +0000, Ian Campbell wrote:
> # HG changeset patch
> # User Ian Campbell <ian.campbell@xxxxxxxxxx>
> # Date 1320922479 0
> # Node ID bc79b560aafa1e4dc42af00e6a326dc651b5636a
> # Parent 460b507e15f864dd6712f5040e36538d6e076ae4
> libxl: use named options for tsc_mode.
>
> It seems that this knob is expoerted from the hypervisor as a raw
> integer (no symbolic names) documented in xen/include/asm-x86. Propagating
> that
> all the way to the end user is hardly friendly (it's bad enough in the
> hypercall interface).
I've just seen docs/misc/tscmode.txt which is actually a pretty
comprehensive explanation of what's going on so the above is
unwarranted. I'll update this patch to include a reference in the
xl-domain-config.
>
> Add an enum at the libxl level with a hopefully descriptive set of names.
> Deprecate the use of an integer in xl cfg files.
I think the naming at the libxl level is still useful even if the values
are documented.
Ian.
>
> Signed-off-by: Ian Campbell
>
> diff -r 460b507e15f8 -r bc79b560aafa docs/user/xl-domain-config.markdown
> --- a/docs/user/xl-domain-config.markdown Thu Nov 10 10:18:29 2011 +0000
> +++ b/docs/user/xl-domain-config.markdown Thu Nov 10 10:54:39 2011 +0000
> @@ -1,4 +1,4 @@
> - # xl Domain Configuration
> +# xl Domain Configuration
>
> To create a VM (a domain in Xen terminology, sometimes called a guest)
> with xl requires the provision of a domain config file. Typically
> @@ -338,6 +338,29 @@ accept the defaults for these options wh
> extensions (e.g. Windows XP compatibility mode on more modern
> Windows OS).
>
> +### Guest Virtual Time Controls
> +
> + * `tsc_mode="MODE"`: Specifies how the TSC (Time Stamp Counter)
> + should be provided to the guest (X86 only). Specifying this option as a
> number
> + is deprecated. Options are:
> +
> + * `"default"`: guest rdtsc/p executed natively when monotonicity
> + can be guaranteed and emulated otherwise (with frequency scaled
> + if necessary).
> +
> + * `"always_emulate"`: guest rdtsc/p always emulated at 1GHz (kernel
> + and user).
> +
> + * `"native"`: guest rdtsc always executed natively (no
> + monotonicity/frequency guarantees); guest rdtscp emulated at
> + native frequency if unsupported by h/w, else executed natively.
> +
> + * `"native_paravirt"`: same as `native`, except xen manages TSC_AUX
> + register so guest can determine when a restore/migration has
> + occurred and assumes guest obtains/uses pvclock-like mechanism
> + to adjust for monotonicity and frequency changes.
> +
> +
> ### Support for Paravirtualisation of HVM Guests
>
> The following options allow Paravirtualised features (such as devices)
> @@ -546,9 +569,6 @@ certainly belong in a more appropriate s
> enables certain other features which are incompatible with
> migration (currently certain TSC modes XXX ?).
>
> - * `tsc_mode=VALUE`: Specifies how the TSC (Time Stamp Counter) should
> - be provided to the guest. XXX ???
> -
> * `pci_msitranslate=BOOLEAN`: XXX
>
> * `pci_power_mgmt=BOOLEAN`: XXX
> diff -r 460b507e15f8 -r bc79b560aafa tools/libxl/libxl_dom.c
> --- a/tools/libxl/libxl_dom.c Thu Nov 10 10:18:29 2011 +0000
> +++ b/tools/libxl/libxl_dom.c Thu Nov 10 10:54:39 2011 +0000
> @@ -73,12 +73,29 @@ int libxl__build_pre(libxl__gc *gc, uint
> libxl_domain_build_info *info, libxl__domain_build_state
> *state)
> {
> libxl_ctx *ctx = libxl__gc_owner(gc);
> + int tsc_mode;
> xc_domain_max_vcpus(ctx->xch, domid, info->max_vcpus);
> xc_domain_setmaxmem(ctx->xch, domid, info->target_memkb +
> LIBXL_MAXMEM_CONSTANT);
> if (info->type == LIBXL_DOMAIN_TYPE_PV)
> xc_domain_set_memmap_limit(ctx->xch, domid,
> (info->max_memkb + info->u.pv.slack_memkb));
> - xc_domain_set_tsc_info(ctx->xch, domid, info->tsc_mode, 0, 0, 0);
> + switch (info->tsc_mode) {
> + case LIBXL_TSC_MODE_DEFAULT:
> + tsc_mode = 0;
> + break;
> + case LIBXL_TSC_MODE_ALWAYS_EMULATE:
> + tsc_mode = 1;
> + break;
> + case LIBXL_TSC_MODE_NATIVE:
> + tsc_mode = 2;
> + break;
> + case LIBXL_TSC_MODE_NATIVE_PARAVIRT:
> + tsc_mode = 3;
> + break;
> + default:
> + abort();
> + }
> + xc_domain_set_tsc_info(ctx->xch, domid, tsc_mode, 0, 0, 0);
> if ( info->disable_migrate )
> xc_domain_disable_migrate(ctx->xch, domid);
>
> diff -r 460b507e15f8 -r bc79b560aafa tools/libxl/libxl_types.idl
> --- a/tools/libxl/libxl_types.idl Thu Nov 10 10:18:29 2011 +0000
> +++ b/tools/libxl/libxl_types.idl Thu Nov 10 10:54:39 2011 +0000
> @@ -85,6 +85,13 @@ libxl_button = Enumeration("button", [
> (2, "SLEEP"),
> ])
>
> +libxl_tsc_mode = Enumeration("tsc_mode", [
> + (0, "default"),
> + (1, "always_emulate"),
> + (2, "native"),
> + (3, "native_paravirt"),
> + ])
> +
> #
> # Complex libxl types
> #
> @@ -154,7 +161,7 @@ libxl_domain_create_info = Struct("domai
> libxl_domain_build_info = Struct("domain_build_info",[
> ("max_vcpus", integer),
> ("cur_vcpus", integer),
> - ("tsc_mode", integer),
> + ("tsc_mode", libxl_tsc_mode),
> ("max_memkb", uint32),
> ("target_memkb", uint32),
> ("video_memkb", uint32),
> diff -r 460b507e15f8 -r bc79b560aafa tools/libxl/xl_cmdimpl.c
> --- a/tools/libxl/xl_cmdimpl.c Thu Nov 10 10:18:29 2011 +0000
> +++ b/tools/libxl/xl_cmdimpl.c Thu Nov 10 10:54:39 2011 +0000
> @@ -328,7 +328,7 @@ static void printf_info(int domid,
>
> printf("\t(build_info)\n");
> printf("\t(max_vcpus %d)\n", b_info->max_vcpus);
> - printf("\t(tsc_mode %d)\n", b_info->tsc_mode);
> + printf("\t(tsc_mode %s)\n", libxl_tsc_mode_to_string(b_info->tsc_mode));
> printf("\t(max_memkb %d)\n", b_info->max_memkb);
> printf("\t(target_memkb %d)\n", b_info->target_memkb);
> printf("\t(nomigrate %d)\n", b_info->disable_migrate);
> @@ -662,8 +662,23 @@ static void parse_config_data(const char
> if (!xlu_cfg_get_long (config, "nomigrate", &l, 0))
> b_info->disable_migrate = l;
>
> - if (!xlu_cfg_get_long(config, "tsc_mode", &l, 0))
> + if (!xlu_cfg_get_long(config, "tsc_mode", &l, 1)) {
> + fprintf(stderr, "WARNING: specifying \"tsc_mode\" as an integer is
> deprecated. "
> + "Please use the named parameter variant.\n");
> + if (l < LIBXL_TSC_MODE_DEFAULT ||
> + l > LIBXL_TSC_MODE_NATIVE_PARAVIRT) {
> + fprintf(stderr, "ERROR: invalid value %ld for \"tsc_mode\"\n",
> l);
> + exit (1);
> + }
> b_info->tsc_mode = l;
> + } else if (!xlu_cfg_get_string(config, "tsc_mode", &buf, 0)) {
> + fprintf(stderr, "got a tsc mode string: \"%s\"\n", buf);
> + if (libxl_tsc_mode_from_string(buf, &b_info->tsc_mode)) {
> + fprintf(stderr, "ERROR: invalid value \"%s\" for \"tsc_mode\"\n",
> + buf);
> + exit (1);
> + }
> + }
>
> if (!xlu_cfg_get_long (config, "videoram", &l, 0))
> b_info->video_memkb = l * 1024;
>
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