Hi David, > On Oct 21, 2015, at 05:29 , David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> wrote: > > On Wed, Aug 26, 2015 at 09:44:33PM +0300, Pantelis Antoniou wrote: >> This patch enable the generation of symbols & local fixup information >> for trees compiled with the -@ (--symbols) option. >> >> Using this patch labels in the tree and their users emit information >> in __symbols__ and __local_fixups__ nodes. >> >> The __fixups__ node make possible the dynamic resolution of phandle >> references which are present in the plugin tree but lie in the >> tree that are applying the overlay against. >> >> panto: The original alternative syntax patch required the use of an empty node >> which is no longer required. >> Numbering of fragments in sequence was also implemented. >> >> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx> >> Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> >> Signed-off-by: Jan Luebbe <jlu@xxxxxxxxxxxxxx> > > Sorry it's taken me so very long to look at this. I've been a bit > swamped by critical bugs in my day job. > No worries. > As I've said before (and say several times below), I don't much like > the fixups/symbols format, but it's in use so I guess we're stuck with > it. > > So, the concept and behaviour of this patch seems mostly fine to me. > I've made a number of comments below. Some are just trivial nits, but > a few are important implementation problems that could lead to nasty > behaviour in edge cases. > >> --- >> Documentation/manual.txt | 16 ++++ >> checks.c | 18 ++++- >> dtc-lexer.l | 5 ++ >> dtc-parser.y | 54 +++++++++++-- >> dtc.c | 21 ++++- >> dtc.h | 13 ++- >> livetree.c | 202 +++++++++++++++++++++++++++++++++++++++++++++++ >> treesource.c | 3 + >> 8 files changed, 321 insertions(+), 11 deletions(-) >> >> diff --git a/Documentation/manual.txt b/Documentation/manual.txt >> index 398de32..29682df 100644 >> --- a/Documentation/manual.txt >> +++ b/Documentation/manual.txt >> @@ -119,6 +119,20 @@ Options: >> Make space for <number> reserve map entries >> Relevant for dtb and asm output only. >> >> + -@ >> + Generates a __symbols__ node at the root node of the resulting blob > > Nit: indentation error here. > OK. >> + for any node labels used, and for any local references using phandles >> + it also generates a __local_fixups__ node that tracks them. >> + >> + When using the /plugin/ tag all unresolved label references to >> + be tracked in the __fixups__ node, making dynamic resolution possible. >> + >> + -A >> + Generate automatically aliases for all node labels. This is similar to >> + the -@ option (the __symbols__ node contain identical information) but >> + the semantics are slightly different since no phandles are automatically >> + generated for labeled nodes. >> + >> -S <bytes> >> Ensure the blob at least <bytes> long, adding additional >> space if needed. >> @@ -153,6 +167,8 @@ Here is a very rough overview of the layout of a DTS source file: >> >> devicetree: '/' nodedef >> >> + plugindecl: '/' 'plugin' '/' ';' >> + >> nodedef: '{' list_of_property list_of_subnode '}' ';' >> >> property: label PROPNAME '=' propdata ';' >> diff --git a/checks.c b/checks.c >> index 0c03ac9..65bf6fd 100644 >> --- a/checks.c >> +++ b/checks.c >> @@ -466,8 +466,12 @@ static void fixup_phandle_references(struct check *c, struct node *dt, >> >> refnode = get_node_by_ref(dt, m->ref); >> if (! refnode) { >> - FAIL(c, "Reference to non-existent node or label \"%s\"\n", >> - m->ref); >> + if (!source_is_plugin) >> + FAIL(c, "Reference to non-existent node or " >> + "label \"%s\"\n", m->ref); >> + else /* mark the entry as unresolved */ >> + *((cell_t *)(prop->val.val + m->offset)) = >> + cpu_to_fdt32(0xffffffff); >> continue; >> } >> >> @@ -652,6 +656,15 @@ static void check_obsolete_chosen_interrupt_controller(struct check *c, >> } >> TREE_WARNING(obsolete_chosen_interrupt_controller, NULL); >> >> +static void check_deprecated_plugin_syntax(struct check *c, >> + struct node *dt) >> +{ >> + if (deprecated_plugin_syntax_warning) >> + FAIL(c, "Use '/dts-v1/ /plugin/'; syntax. /dts-v1/; /plugin/; " >> + "is going to be removed in next versions"); > > Better to put this warning directly where the bad syntax is detected > in the parser (using ERROR), transferring it to here with the global > is pretty ugly. > > The checks infrastructure isn't meant to handle all possible error > conditions - just those that are related to the tree's semantic > content, rather than pars > > Plus.. the old syntax was never committed upstream, so I'm inclined to > just drop it now, making this irrelevant. > OK, I will drop the deprecated syntax, but I will maintain an out of tree patch for people that still keep old style DTSes around. >> +} >> +TREE_WARNING(deprecated_plugin_syntax, NULL); >> + >> static struct check *check_table[] = { >> &duplicate_node_names, &duplicate_property_names, >> &node_name_chars, &node_name_format, &property_name_chars, >> @@ -669,6 +682,7 @@ static struct check *check_table[] = { >> >> &avoid_default_addr_size, >> &obsolete_chosen_interrupt_controller, >> + &deprecated_plugin_syntax, >> >> &always_fail, >> }; >> diff --git a/dtc-lexer.l b/dtc-lexer.l >> index 0ee1caf..dd44ba2 100644 >> --- a/dtc-lexer.l >> +++ b/dtc-lexer.l >> @@ -113,6 +113,11 @@ static void lexical_error(const char *fmt, ...); >> return DT_V1; >> } >> >> +<*>"/plugin/" { >> + DPRINT("Keyword: /plugin/\n"); >> + return DT_PLUGIN; >> + } >> + >> <*>"/memreserve/" { >> DPRINT("Keyword: /memreserve/\n"); >> BEGIN_DEFAULT(); >> diff --git a/dtc-parser.y b/dtc-parser.y >> index 5a897e3..accccba 100644 >> --- a/dtc-parser.y >> +++ b/dtc-parser.y >> @@ -19,6 +19,7 @@ >> */ >> %{ >> #include <stdio.h> >> +#include <inttypes.h> >> >> #include "dtc.h" >> #include "srcpos.h" >> @@ -52,9 +53,11 @@ extern bool treesource_error; >> struct node *nodelist; >> struct reserve_info *re; >> uint64_t integer; >> + bool is_plugin; >> } >> >> %token DT_V1 >> +%token DT_PLUGIN >> %token DT_MEMRESERVE >> %token DT_LSHIFT DT_RSHIFT DT_LE DT_GE DT_EQ DT_NE DT_AND DT_OR >> %token DT_BITS >> @@ -71,6 +74,7 @@ extern bool treesource_error; >> >> %type <data> propdata >> %type <data> propdataprefix >> +%type <is_plugin> plugindecl >> %type <re> memreserve >> %type <re> memreserves >> %type <array> arrayprefix >> @@ -101,10 +105,39 @@ extern bool treesource_error; >> %% >> >> sourcefile: >> - DT_V1 ';' memreserves devicetree >> + basesource >> + | pluginsource >> + ; >> + >> +basesource: >> + DT_V1 ';' plugindecl memreserves devicetree >> + { >> + source_is_plugin = $3; >> + if (source_is_plugin) >> + deprecated_plugin_syntax_warning = true; >> + the_boot_info = build_boot_info($4, $5, >> + guess_boot_cpuid($5)); >> + } >> + ; >> + >> +plugindecl: >> + /* empty */ >> + { >> + $$ = false; >> + } >> + | DT_PLUGIN ';' >> + { >> + $$ = true; >> + } >> + ; >> + >> +pluginsource: >> + DT_V1 DT_PLUGIN ';' memreserves devicetree >> { >> - the_boot_info = build_boot_info($3, $4, >> - guess_boot_cpuid($4)); >> + source_is_plugin = true; >> + deprecated_plugin_syntax_warning = false; >> + the_boot_info = build_boot_info($4, $5, >> + guess_boot_cpuid($5)); >> } > > I think the above will be clearer if you make a new non-terminal, say > 'versioninfo', that incorporates the DT_V1 and (optionally) the > /plugin/ tag. We can extend that with other global flags if we ever > need them. > OK. >> ; >> >> @@ -156,10 +189,14 @@ devicetree: >> { >> struct node *target = get_node_by_ref($1, $2); >> >> - if (target) >> + if (target) { >> merge_nodes(target, $3); >> - else >> - ERROR(&@2, "Label or path %s not found", $2); >> + } else { >> + if (symbol_fixup_support) >> + add_orphan_node($1, $3, $2); >> + else >> + ERROR(&@2, "Label or path %s not found", $2); >> + } >> $$ = $1; >> } >> | devicetree DT_DEL_NODE DT_REF ';' >> @@ -174,6 +211,11 @@ devicetree: >> >> $$ = $1; >> } >> + | /* empty */ >> + { >> + /* build empty node */ >> + $$ = name_node(build_node(NULL, NULL), ""); >> + } >> ; > > What's the importance of this new rule? It's connection to plugins > isn't obvious to me. > It is required when you use the syntactic sugar version of an overlay definition. &target { foo; }; >> >> nodedef: >> diff --git a/dtc.c b/dtc.c >> index 5fa23c4..ee37be9 100644 >> --- a/dtc.c >> +++ b/dtc.c >> @@ -31,6 +31,8 @@ int reservenum; /* Number of memory reservation slots */ >> int minsize; /* Minimum blob size */ >> int padsize; /* Additional padding to blob */ >> int phandle_format = PHANDLE_BOTH; /* Use linux,phandle or phandle properties */ >> +int symbol_fixup_support; >> +int auto_label_aliases; >> >> static void fill_fullpaths(struct node *tree, const char *prefix) >> { >> @@ -53,7 +55,7 @@ static void fill_fullpaths(struct node *tree, const char *prefix) >> #define FDT_VERSION(version) _FDT_VERSION(version) >> #define _FDT_VERSION(version) #version >> static const char usage_synopsis[] = "dtc [options] <input file>"; >> -static const char usage_short_opts[] = "qI:O:o:V:d:R:S:p:fb:i:H:sW:E:hv"; >> +static const char usage_short_opts[] = "qI:O:o:V:d:R:S:p:fb:i:H:sW:E:@Ahv"; >> static struct option const usage_long_opts[] = { >> {"quiet", no_argument, NULL, 'q'}, >> {"in-format", a_argument, NULL, 'I'}, >> @@ -71,6 +73,8 @@ static struct option const usage_long_opts[] = { >> {"phandle", a_argument, NULL, 'H'}, >> {"warning", a_argument, NULL, 'W'}, >> {"error", a_argument, NULL, 'E'}, >> + {"symbols", no_argument, NULL, '@'}, >> + {"auto-alias", no_argument, NULL, 'A'}, >> {"help", no_argument, NULL, 'h'}, >> {"version", no_argument, NULL, 'v'}, >> {NULL, no_argument, NULL, 0x0}, >> @@ -101,6 +105,8 @@ static const char * const usage_opts_help[] = { >> "\t\tboth - Both \"linux,phandle\" and \"phandle\" properties", >> "\n\tEnable/disable warnings (prefix with \"no-\")", >> "\n\tEnable/disable errors (prefix with \"no-\")", >> + "\n\tEnable symbols/fixup support", >> + "\n\tEnable auto-alias of labels", >> "\n\tPrint this help and exit", >> "\n\tPrint version and exit", >> NULL, >> @@ -233,7 +239,12 @@ int main(int argc, char *argv[]) >> case 'E': >> parse_checks_option(false, true, optarg); >> break; >> - >> + case '@': >> + symbol_fixup_support = 1; >> + break; >> + case 'A': >> + auto_label_aliases = 1; >> + break; >> case 'h': >> usage(NULL); >> default: >> @@ -294,6 +305,12 @@ int main(int argc, char *argv[]) >> if (sort) >> sort_tree(bi); >> >> + if (symbol_fixup_support || auto_label_aliases) >> + generate_label_node(bi->dt, bi->dt); >> + >> + if (symbol_fixup_support) >> + generate_fixups_node(bi->dt, bi->dt); >> + >> if (streq(outname, "-")) { >> outf = stdout; >> } else { >> diff --git a/dtc.h b/dtc.h >> index 56212c8..d025111 100644 >> --- a/dtc.h >> +++ b/dtc.h >> @@ -20,7 +20,7 @@ >> * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 >> * USA >> */ >> - >> +#define _GNU_SOURCE > > Ugh.. I'm at least trying to keep dtc compilable on FreeBSD, so I'd > prefer to avoid using GNU extensions. What's the feature you needed > this for? > Hmm, it’s for using asprintf. Funnily asprintf is already used in the srcpos.c file, which is used for the converter. I can easily switch to sprintf with some hit to readability. >> #include <stdio.h> >> #include <string.h> >> #include <stdlib.h> >> @@ -54,6 +54,14 @@ extern int reservenum; /* Number of memory reservation slots */ >> extern int minsize; /* Minimum blob size */ >> extern int padsize; /* Additional padding to blob */ >> extern int phandle_format; /* Use linux,phandle or phandle properties */ >> +extern int symbol_fixup_support;/* enable symbols & fixup support */ >> +extern int auto_label_aliases; /* auto generate labels -> aliases */ >> + >> +/* >> + * Tree source globals >> + */ >> +extern bool source_is_plugin; > > I think it makes sense to put this flag into the_boot_info, rather > than adding a new global. OK > >> +extern bool deprecated_plugin_syntax_warning; > > And as noted above, I don't think you need this one at all. > OK. >> #define PHANDLE_LEGACY 0x1 >> #define PHANDLE_EPAPR 0x2 >> @@ -194,6 +202,7 @@ struct node *build_node_delete(void); >> struct node *name_node(struct node *node, char *name); >> struct node *chain_node(struct node *first, struct node *list); >> struct node *merge_nodes(struct node *old_node, struct node *new_node); >> +void add_orphan_node(struct node *old_node, struct node *new_node, char *ref); >> >> void add_property(struct node *node, struct property *prop); >> void delete_property_by_name(struct node *node, char *name); >> @@ -244,6 +253,8 @@ struct boot_info { >> struct boot_info *build_boot_info(struct reserve_info *reservelist, >> struct node *tree, uint32_t boot_cpuid_phys); >> void sort_tree(struct boot_info *bi); >> +void generate_label_node(struct node *node, struct node *dt); >> +void generate_fixups_node(struct node *node, struct node *dt); >> >> /* Checks */ >> >> diff --git a/livetree.c b/livetree.c >> index e229b84..1ef9fc4 100644 >> --- a/livetree.c >> +++ b/livetree.c >> @@ -216,6 +216,34 @@ struct node *merge_nodes(struct node *old_node, struct node *new_node) >> return old_node; >> } >> >> +void add_orphan_node(struct node *dt, struct node *new_node, char *ref) >> +{ >> + static unsigned int next_orphan_fragment = 0; >> + struct node *ovl = xmalloc(sizeof(*ovl)); >> + struct property *p; >> + struct data d = empty_data; >> + char *name; >> + int ret; >> + >> + memset(ovl, 0, sizeof(*ovl)); >> + >> + d = data_add_marker(d, REF_PHANDLE, ref); >> + d = data_append_integer(d, 0xffffffff, 32); >> + p = build_property("target", d); >> + add_property(ovl, p); > > Hmm, using a phandle (which has to be later mangled) rather than a > string ref directly in the target property seems an unnecessarily > difficult way of doing things, but I guess the format's in use so we > can't fix that now. It makes sense in practice though and it makes this to work: &target { foo; }; > >> + ret = asprintf(&name, "fragment@%u", >> + next_orphan_fragment++); >> + if (ret == -1) >> + die("asprintf() failed\n"); >> + name_node(ovl, name); >> + name_node(new_node, "__overlay__"); > > It's a bit confusing to me that it's the original node, not 'ovl' > which gets the name "__overlay__". Maybe a different variable name. > > This could produce some confusing results if a plugin source contains > a "base" tree construction. > This is part of the syntactic sugar part. I will change the names of the variables to make things clearer. >> + add_child(dt, ovl); >> + add_child(ovl, new_node); >> +} >> + >> struct node *chain_node(struct node *first, struct node *list) >> { >> assert(first->next_sibling == NULL); >> @@ -709,3 +737,177 @@ void sort_tree(struct boot_info *bi) >> sort_reserve_entries(bi); >> sort_node(bi->dt); >> } >> + >> +void generate_label_node(struct node *node, struct node *dt) > > I prefer to put "context" parameters before more specific parameters, > so I'd like to see dt then node. Also, maybe call it 'tree', since > that seems to be the more common name in livetree.c. > OK. >> +{ >> + struct node *c, *an; >> + struct property *p; >> + struct label *l; >> + int has_label; >> + char *gen_node_name; >> + >> + if (auto_label_aliases) >> + gen_node_name = "aliases"; >> + else >> + gen_node_name = "__symbols__"; > > Doing just one or the other here also seems dubious to me, as does > referencing the global here. I'd prefer to see this as a parameter, > which the main function can pass in. That way you can also better > handle the case of using both -A and -@ at the same time. > I’ll see what I can do… there were some complications when I tried it. > I also think it would be nice to construct the alias/symbols node just > once for the tree then pass the reference to the recursive call. > Hmm… maybe. I’ll give it a whirl. > >> + >> + /* Make sure the label isn't already there */ > > Comment doesn't match the code, this just tests if the node has a > label at all. For which 'if (node-labels)' would suffice. > Comment will be deleted. Probably a leftover. >> + has_label = 0; >> + for_each_label(node->labels, l) { >> + has_label = 1; >> + break; >> + } >> + >> + if (has_label) { >> + > > Nit: extraneous blank line. > OK. (geeze) >> + /* an is the aliases/__symbols__ node */ >> + an = get_subnode(dt, gen_node_name); >> + /* if no node exists, create it */ >> + if (!an) { >> + an = build_node(NULL, NULL); >> + name_node(an, gen_node_name); >> + add_child(dt, an); >> + } >> + >> + /* now add the label in the node */ >> + for_each_label(node->labels, l) { >> + /* check whether the label already exists */ >> + p = get_property(an, l->label); >> + if (p) { >> + fprintf(stderr, "WARNING: label %s already" >> + " exists in /%s", l->label, >> + gen_node_name); >> + continue; >> + } >> + >> + /* insert it */ >> + p = build_property(l->label, >> + data_copy_escape_string(node->fullpath, >> + strlen(node->fullpath))); > > fullpath should not contain escape characters, and if it does you > shouldn't be unescaping them, so data_copy_escape_string() is the > wrong tool for this job. > OK. >> + add_property(an, p); >> + } >> + >> + /* force allocation of a phandle for this node */ >> + if (symbol_fixup_support) >> + (void)get_node_phandle(dt, node); > > Again, I'd prefer to see a parameter rather than referencing the global. > OK >> + } >> + >> + for_each_child(node, c) >> + generate_label_node(c, dt); >> +} >> + >> +static void add_fixup_entry(struct node *dt, struct node *node, >> + struct property *prop, struct marker *m) >> +{ >> + struct node *fn; /* local fixup node */ >> + struct property *p; >> + char *fixups_name = "__fixups__"; >> + struct data d; >> + char *entry; >> + int ret; >> + >> + /* fn is the node we're putting entries in */ >> + fn = get_subnode(dt, fixups_name); >> + /* if no node exists, create it */ >> + if (!fn) { >> + fn = build_node(NULL, NULL); >> + name_node(fn, fixups_name); >> + add_child(dt, fn); >> + } > > Again, I'd prefer to see construction and location of the fixups node > factored out. > OK. >> + >> + ret = asprintf(&entry, "%s:%s:%u", >> + node->fullpath, prop->name, m->offset); > > I hate this encoding of things into a string that will have to be > parsed, rather than using the existing mechanisms we have for > structure in the tree. But, again, the format is in use so I guess > we're stuck with it. > > I would at least like to see this throw an error if the path or the > property name include ':' characters that will mess this up. > Will do. > >> + if (ret == -1) >> + die("asprintf() failed\n"); > > Hrm. We should put an xasprintf function in util. That also lets us > supply our own implementation when necessary and avoid relying on the > gnu extension. > I think that would be best. >> + >> + p = get_property(fn, m->ref); > > This doesn't handle the case where m->ref is a path rather than a > label. It will lead to creating a property with '/' in the name > below, which you really don't want. > I haven’t thought of the m->ref being a path. Will guard against it. >> + d = data_append_data(p ? p->val : empty_data, entry, strlen(entry) + 1); >> + if (!p) >> + add_property(fn, build_property(m->ref, d)); >> + else >> + p->val = d; > > I think this would be clearer with just a single if, rather than an if > and the parallel conditional expression. > OK. >> +} >> + >> +static void add_local_fixup_entry(struct node *dt, struct node *node, >> + struct property *prop, struct marker *m, >> + struct node *refnode) >> +{ >> + struct node *lfn, *wn, *nwn; /* local fixup node, walk node, new */ >> + struct property *p; >> + struct data d; >> + char *local_fixups_name = "__local_fixups__"; >> + char *s, *e, *comp; >> + int len; >> + >> + /* fn is the node we're putting entries in */ >> + lfn = get_subnode(dt, local_fixups_name); >> + /* if no node exists, create it */ >> + if (!lfn) { >> + lfn = build_node(NULL, NULL); >> + name_node(lfn, local_fixups_name); >> + add_child(dt, lfn); >> + } > > Again, please factor the node creation. > OK >> + >> + /* walk the path components creating nodes if they don't exist */ > > Might be worth making a helper function for this operation. As it is, > it somewhat obscures the fixup logic that this function is actually > about. > OK > It also seems absurd to me that the local fixups take such a > completely different format from the non-local fixups. But, yet > again, stuck with it. > I explained before, there’s a reason for it :) >> + comp = NULL; >> + /* start skipping the first / */ >> + s = node->fullpath + 1; >> + wn = lfn; >> + while (*s) { >> + /* retrieve path component */ >> + e = strchr(s, '/'); >> + if (e == NULL) >> + e = s + strlen(s); >> + len = e - s; >> + comp = xrealloc(comp, len + 1); > > You can just allocate comp with strlen(fullpath) bytes in the first > place, rather than realloc()ing on every iteration. > OK >> + memcpy(comp, s, len); >> + comp[len] = '\0'; >> + >> + /* if no node exists, create it */ >> + nwn = get_subnode(wn, comp); >> + if (!nwn) { >> + nwn = build_node(NULL, NULL); >> + name_node(nwn, strdup(comp)); >> + add_child(wn, nwn); > > This build/name/add tuple appears in a bunch of places in your code, > might be worth a helper function for that too. > OK >> + } >> + wn = nwn; >> + >> + /* last path component */ >> + if (!*e) >> + break; >> + >> + /* next path component */ >> + s = e + 1; >> + } >> + free(comp); >> + >> + p = get_property(wn, prop->name); >> + d = data_append_cell(p ? p->val : empty_data, (cell_t)m->offset); >> + if (!p) >> + add_property(wn, build_property(prop->name, d)); >> + else >> + p->val = d; >> +} >> + >> +void generate_fixups_node(struct node *node, struct node *dt) >> +{ >> + struct node *c; >> + struct property *prop; >> + struct marker *m; >> + struct node *refnode; >> + >> + for_each_property(node, prop) { >> + m = prop->val.markers; >> + for_each_marker_of_type(m, REF_PHANDLE) { >> + refnode = get_node_by_ref(dt, m->ref); >> + if (!refnode) >> + add_fixup_entry(dt, node, prop, m); >> + else >> + add_local_fixup_entry(dt, node, prop, m, >> + refnode); > > Do you need to consider REF_PATH fixups? > I don’t think so, but I will take a look. >> + } >> + } >> + >> + for_each_child(node, c) >> + generate_fixups_node(c, dt); >> +} >> diff --git a/treesource.c b/treesource.c >> index a55d1d1..e1d6657 100644 >> --- a/treesource.c >> +++ b/treesource.c >> @@ -28,6 +28,9 @@ extern YYLTYPE yylloc; >> struct boot_info *the_boot_info; >> bool treesource_error; >> >> +bool source_is_plugin; >> +bool deprecated_plugin_syntax_warning; >> + >> struct boot_info *dt_from_source(const char *fname) >> { >> the_boot_info = NULL; > It’s going to take a couple of days for the updated patch to be sent. Thanks for the review. > -- > David Gibson | I'll have my music baroque, and my code > david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ > | _way_ _around_! > http://www.ozlabs.org/~dgibson Regards — Pantelis -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html