Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753820AbdLFBpp (ORCPT ); Tue, 5 Dec 2017 20:45:45 -0500 Received: from out4-smtp.messagingengine.com ([66.111.4.28]:58119 "EHLO out4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753274AbdLFBpn (ORCPT ); Tue, 5 Dec 2017 20:45:43 -0500 X-ME-Sender: From: "Tobin C. Harding" To: Jonathan Corbet Cc: "Tobin C. Harding" , Randy Dunlap , Andrew Murray , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] doc: convert printk-formats.txt to rst Date: Wed, 6 Dec 2017 12:45:29 +1100 Message-Id: <1512524729-16051-1-git-send-email-me@tobin.cc> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 28652 Lines: 795 Documentation/printk-formats.txt is a candidate for conversion to ReStructuredText format. Some effort has already been made to do this conversion even thought the suffix is currently .txt Changes required to complete conversion - Add double backticks where needed. - Add entry to Documentation/index.rst - Use flat-table instead of ASCII table. - Fix minor grammatical errors. - Capitalize headers and correctly order heading adornments. - Use 'Passed by reference' uniformly. - Update pointer documentation around %px specifier. - Fix erroneous double backticks (to commas). - Simplify documentation for kobject. - Convert lib/vsnprintf.c function docs to use kernel-docs and include in Documentation/printk-formats.rst Signed-off-by: Tobin C. Harding --- The last two need special reviewing please. In particular the conversion of kernel-docs in vsnprintf.c attempt was made to reduce documentation duplication with comments in the source code being simplified in order to be suitable for inclusion in Documentation/printk-formats.rst I used -M when formatting the patch. If you don't like the diff with this flag just holla. thanks, Tobin. Documentation/index.rst | 10 + .../{printk-formats.txt => printk-formats.rst} | 295 ++++++++++++--------- lib/vsprintf.c | 160 +++++------ 3 files changed, 235 insertions(+), 230 deletions(-) rename Documentation/{printk-formats.txt => printk-formats.rst} (61%) diff --git a/Documentation/index.rst b/Documentation/index.rst index cb7f1ba5b3b1..83ace60efbe7 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -87,6 +87,16 @@ implementation. sh/index +Miscellaneous documentation +--------------------------- + +These guides contain general information useful when writing kernel code. + +.. toctree:: + :maxdepth: 1 + + printk-formats + Korean translations ------------------- diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.rst similarity index 61% rename from Documentation/printk-formats.txt rename to Documentation/printk-formats.rst index aa0a776c817a..51449d213748 100644 --- a/Documentation/printk-formats.txt +++ b/Documentation/printk-formats.rst @@ -1,6 +1,6 @@ -========================================= -How to get printk format specifiers right -========================================= +============================================= +How to Get ``printk`` Format Specifiers Right +============================================= :Author: Randy Dunlap :Author: Andrew Murray @@ -8,56 +8,91 @@ How to get printk format specifiers right Integer types ============= -:: +For printing integer types, we have the following format specifiers: + + .. flat-table:: + :widths: 2 2 + + * - **Type** + - **Specifier** + + * - ``int`` + - ``%d`` or ``%x`` + + * - ``unsigned int`` + - ``%u`` or ``%x`` + + * - ``long`` + - ``%ld`` or ``%lx`` + + * - ``unsigned long`` + - ``%lu`` or ``%lx`` + + * - ``long long`` + - ``%lld`` or ``%llx`` - If variable is of Type, use printk format specifier: - ------------------------------------------------------------ - int %d or %x - unsigned int %u or %x - long %ld or %lx - unsigned long %lu or %lx - long long %lld or %llx - unsigned long long %llu or %llx - size_t %zu or %zx - ssize_t %zd or %zx - s32 %d or %x - u32 %u or %x - s64 %lld or %llx - u64 %llu or %llx - -If is dependent on a config option for its size (e.g., ``sector_t``, + * - ``unsigned long long`` + - ``%llu`` or ``%llx`` + + * - ``size_t`` + - ``%zu`` or ``%zx`` + + * - ``ssize_t`` + - ``%zd`` or ``%zx`` + + * - ``s32`` + - ``%d`` or ``%x`` + + * - ``u32`` + - ``%u`` or ``%x`` + + * - ``s64`` + - ``%lld`` or ``%llx`` + + * - ``u64`` + - ``%llu`` or ``%llx`` + + +If ```` is dependent on a config option for its size (e.g., ``sector_t``, ``blkcnt_t``) or is architecture-dependent for its size (e.g., ``tcflag_t``), use a format specifier of its largest possible type and explicitly cast to it. Example:: - printk("test: sector number/total blocks: %llu/%llu\n", - (unsigned long long)sector, (unsigned long long)blockcount); + printk("test: total blocks: %llu\n", (unsigned long long)blockcount); -Reminder: ``sizeof()`` result is of type ``size_t``. +Reminder: ``sizeof()`` returns type ``size_t``. -The kernel's printf does not support ``%n``. For obvious reasons, floating +The kernel's printf does not support ``%n``. For obvious reasons floating point formats (``%e, %f, %g, %a``) are also not recognized. Use of any unsupported specifier or length qualifier results in a WARN and early -return from vsnprintf. - -Raw pointer value SHOULD be printed with %p. The kernel supports -the following extended format specifiers for pointer types: +return from ``vsnprintf()``. Pointer Types ============= -Pointers printed without a specifier extension (i.e unadorned %p) are -hashed to give a unique identifier without leaking kernel addresses to user -space. On 64 bit machines the first 32 bits are zeroed. If you _really_ -want the address see %px below. +A raw pointer value may be printed with ``%p`` which will hash the address +before printing. The Kernel also supports extended specifiers for printing +pointers of different types. + +.. kernel-doc:: lib/vsprintf.c + :doc: Extended Format Pointer Specifiers + + +Plain Pointers +-------------- :: %p abcdef12 or 00000000abcdef12 +Pointers printed without a specifier extension (i.e unadorned ``%p``) are +hashed to give a unique identifier without leaking kernel addresses to user +space. On 64 bit machines the first 32 bits are zeroed. If you *really* +want the address see ``%px`` below. + Symbols/Function Pointers -========================= +------------------------- :: @@ -69,61 +104,60 @@ Symbols/Function Pointers %ps versatile_init %pB prev_fn_of_versatile_init+0x88/0x88 -The ``F`` and ``f`` specifiers are for printing function pointers, -for example, f->func, &gettimeofday. They have the same result as -``S`` and ``s`` specifiers. But they do an extra conversion on -ia64, ppc64 and parisc64 architectures where the function pointers -are actually function descriptors. +The ``F`` and ``f`` specifiers are for printing function pointers, for +example, ``f->func``, ``&gettimeofday``. They have the same result as ``S`` +and ``s`` specifiers. But they do an extra conversion on ia64, ppc64 and +parisc64 architectures where the function pointers are actually function +descriptors. The ``S`` and ``s`` specifiers can be used for printing symbols -from direct addresses, for example, __builtin_return_address(0), -(void *)regs->ip. They result in the symbol name with (``S``) or +from direct addresses, for example, ``__builtin_return_address(0)``, +``(void *)regs->ip``. They result in the symbol name with (``S``) or without (``s``) offsets. If KALLSYMS are disabled then the symbol address is printed instead. The ``B`` specifier results in the symbol name with offsets and should be used when printing stack backtraces. The specifier takes into consideration the effect of compiler optimisations which may occur -when tail-call``s are used and marked with the noreturn GCC attribute. +when tail-call's are used and marked with the ``noreturn`` GCC attribute. Examples:: printk("Going to call: %pF\n", gettimeofday); printk("Going to call: %pF\n", p->func); printk("%s: called from %pS\n", __func__, (void *)_RET_IP_); - printk("%s: called from %pS\n", __func__, - (void *)__builtin_return_address(0)); + printk("%s: called from %pS\n", __func__, (void *)__builtin_return_address(0)); printk("Faulted at %pS\n", (void *)regs->ip); printk(" %s%pB\n", (reliable ? "" : "? "), (void *)*stack); Kernel Pointers -=============== +--------------- :: %pK 01234567 or 0123456789abcdef For printing kernel pointers which should be hidden from unprivileged -users. The behaviour of ``%pK`` depends on the ``kptr_restrict sysctl`` - see -Documentation/sysctl/kernel.txt for more details. +users. The behaviour of ``%pK`` depends on the ``kptr_restrict`` sysctl - +see ``Documentation/sysctl/kernel.txt`` for more details. Unmodified Addresses -==================== +-------------------- :: %px 01234567 or 0123456789abcdef -For printing pointers when you _really_ want to print the address. Please +For printing pointers when you *really* want to print the address. Please consider whether or not you are leaking sensitive information about the -Kernel layout in memory before printing pointers with %px. %px is -functionally equivalent to %lx. %px is preferred to %lx because it is more -uniquely grep'able. If, in the future, we need to modify the way the Kernel -handles printing pointers it will be nice to be able to find the call -sites. +kernel memory layout before printing pointers with ``%px``. ``%px`` is +functionally equivalent to ``%lx`` (or ``%lu``). ``%px``, however, is +preferable because it is more uniquely grep'able. If, in the future, we need +to modify the way the Kernel handles printing pointers we will be better +equipped to find the call sites. Struct Resources -================ +---------------- :: @@ -132,12 +166,13 @@ Struct Resources %pR [mem 0x60000000-0x6fffffff pref] or [mem 0x0000000060000000-0x000000006fffffff pref] -For printing struct resources. The ``R`` and ``r`` specifiers result in a +For printing ``struct resources``. The ``R`` and ``r`` specifiers result in a printed resource with (``R``) or without (``r``) a decoded flags member. + Passed by reference. -Physical addresses types ``phys_addr_t`` -======================================== +Physical Address Types ``phys_addr_t`` +-------------------------------------- :: @@ -145,20 +180,24 @@ Physical addresses types ``phys_addr_t`` For printing a ``phys_addr_t`` type (and its derivatives, such as ``resource_size_t``) which can vary based on build options, regardless of -the width of the CPU data path. Passed by reference. +the width of the CPU data path. + +Passed by reference. -DMA addresses types ``dma_addr_t`` -================================== +DMA Address Types ``dma_addr_t`` +-------------------------------- :: %pad 0x01234567 or 0x0123456789abcdef For printing a ``dma_addr_t`` type which can vary based on build options, -regardless of the width of the CPU data path. Passed by reference. +regardless of the width of the CPU data path. -Raw buffer as an escaped string -=============================== +Passed by reference. + +Raw Buffer as an Escaped String +------------------------------- :: @@ -168,7 +207,7 @@ For printing raw buffer as an escaped string. For the following buffer:: 1b 62 20 5c 43 07 22 90 0d 5d -few examples show how the conversion would be done (the result string +A few examples show how the conversion would be done (the result string without surrounding quotes):: %*pE "\eb \C\a"\220\r]" @@ -194,8 +233,8 @@ printing SSIDs. If field width is omitted the 1 byte only will be escaped. -Raw buffer as a hex string -========================== +Raw Buffer as a Hex String +-------------------------- :: @@ -205,11 +244,11 @@ Raw buffer as a hex string %*phN 000102 ... 3f For printing a small buffers (up to 64 bytes long) as a hex string with -certain separator. For the larger buffers consider to use +certain separator. For the larger buffers consider using :c:func:`print_hex_dump`. -MAC/FDDI addresses -================== +MAC/FDDI Addresses +------------------ :: @@ -233,8 +272,8 @@ of Bluetooth addresses which are in the little endian order. Passed by reference. -IPv4 addresses -============== +IPv4 Addresses +-------------- :: @@ -252,8 +291,8 @@ no specifier is provided the default network/big endian order is used. Passed by reference. -IPv6 addresses -============== +IPv6 Addresses +-------------- :: @@ -271,8 +310,8 @@ http://tools.ietf.org/html/rfc5952 Passed by reference. -IPv4/IPv6 addresses (generic, with port, flowinfo, scope) -========================================================= +IPv4/IPv6 Addresses (generic, with port, flowinfo or scope) +--------------------------------------------------------------- :: @@ -282,8 +321,8 @@ IPv4/IPv6 addresses (generic, with port, flowinfo, scope) %pISpc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345 %p[Ii]S[pfschnbl] -For printing an IP address without the need to distinguish whether it``s -of type AF_INET or AF_INET6, a pointer to a valid ``struct sockaddr``, +For printing an IP address without the need to distinguish whether it's +of type AF_INET or AF_INET6. A pointer to a valid ``struct sockaddr``, specified through ``IS`` or ``iS``, can be passed to this format specifier. The additional ``p``, ``f``, and ``s`` specifiers are used to specify port @@ -308,8 +347,8 @@ Further examples:: %pISsc 1.2.3.4 or [1:2:3:4:5:6:7:8]%1234567890 %pISpfc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345/123456789 -UUID/GUID addresses -=================== +UUID/GUID Addresses +------------------- :: @@ -318,18 +357,18 @@ UUID/GUID addresses %pUl 03020100-0504-0706-0809-0a0b0c0e0e0f %pUL 03020100-0504-0706-0809-0A0B0C0E0E0F -For printing 16-byte UUID/GUIDs addresses. The additional 'l', 'L', -'b' and 'B' specifiers are used to specify a little endian order in -lower ('l') or upper case ('L') hex characters - and big endian order -in lower ('b') or upper case ('B') hex characters. +For printing 16-byte UUID/GUIDs addresses. The additional ``l``, ``L``, +``b`` and ``B`` specifiers are used to specify a little endian order in +lower (``l``) or upper case (``L``) hex digits - and big endian order +in lower (``b``) or upper case (``B``) hex digits. Where no additional specifiers are used the default big endian -order with lower case hex characters will be printed. +order with lower case hex digits will be printed. Passed by reference. -dentry names -============ +Dentry Names +------------ :: @@ -343,24 +382,24 @@ equivalent of ``%s`` ``dentry->d_name.name`` we used to use, ``%pd`` prints Passed by reference. -block_device names -================== +block_device Names +------------------ :: %pg sda, sda1 or loop0p1 -For printing name of block_device pointers. +For printing name of ``block_device`` pointers. struct va_format -================ +---------------- :: %pV -For printing struct va_format structures. These contain a format string -and va_list as follows:: +For printing ``struct va_format`` structures. These contain a format string +and ``va_list`` as follows:: struct va_format { const char *fmt; @@ -370,36 +409,33 @@ and va_list as follows:: Implements a "recursive vsnprintf". Do not use this feature without some mechanism to verify the -correctness of the format string and va_list arguments. +correctness of the format string and ``va_list`` arguments. Passed by reference. kobjects -======== - +-------- + :: - %pO + %pOF[fnpPcCF] - Base specifier for kobject based structs. Must be followed with - character for specific type of kobject as listed below: - Device tree nodes: +For printing kobject based structs (device nodes). Default behaviour is +equivalent to ``%pOFf``. - %pOF[fnpPcCF] + - ``f`` device node full_name + - ``n`` device node name + - ``p`` device node phandle + - ``P`` device node path spec (name + @unit) + - ``F`` device node flags + - ``c`` major compatible string + - ``C`` full compatible string - For printing device tree nodes. The optional arguments are: - f device node full_name - n device node name - p device node phandle - P device node path spec (name + @unit) - F device node flags - c major compatible string - C full compatible string - Without any arguments prints full_name (same as %pOFf) - The separator when using multiple arguments is ':' +The separator when using multiple arguments is ``:`` - Examples: +Examples: +:: %pOF /foo/bar@0 - Node full name %pOFf /foo/bar@0 - Same as above @@ -412,11 +448,10 @@ kobjects P - Populated B - Populated bus - Passed by reference. - +Passed by reference. struct clk -========== +---------- :: @@ -424,14 +459,14 @@ struct clk %pCn pll1 %pCr 1560000000 -For printing struct clk structures. ``%pC`` and ``%pCn`` print the name +For printing ``struct clk structures``. ``%pC`` and ``%pCn`` print the name (Common Clock Framework) or address (legacy clock framework) of the structure; ``%pCr`` prints the current clock rate. Passed by reference. -bitmap and its derivatives such as cpumask and nodemask -======================================================= +Bitmap and its Derivatives (such as cpumask and nodemask) +--------------------------------------------------------- :: @@ -439,13 +474,13 @@ bitmap and its derivatives such as cpumask and nodemask %*pbl 0,3-6,8-10 For printing bitmap and its derivatives such as cpumask and nodemask, -``%*pb`` output the bitmap with field width as the number of bits and ``%*pbl`` -output the bitmap as range list with field width as the number of bits. +``%*pb`` outputs the bitmap with field width as the number of bits and ``%*pbl`` +outputs the bitmap as range list with field width as the number of bits. Passed by reference. -Flags bitfields such as page flags, gfp_flags -============================================= +Flags Bitfields (such as page flags, gfp_flags) +----------------------------------------------- :: @@ -459,25 +494,27 @@ character. Currently supported are [p]age flags, [v]ma_flags (both expect ``unsigned long *``) and [g]fp_flags (expects ``gfp_t *``). The flag names and print order depends on the particular type. -Note that this format should not be used directly in :c:func:`TP_printk()` part -of a tracepoint. Instead, use the ``show_*_flags()`` functions from -. +Note that this format should not be used directly in the +:c:func:`TP_printk()` part of a tracepoint. Instead, use the +``show_*_flags()`` functions from ````. Passed by reference. -Network device features -======================= +Network Device Features +----------------------- :: %pNF 0x000000000000c000 -For printing netdev_features_t. +For printing ``netdev_features_t``. Passed by reference. -If you add other ``%p`` extensions, please extend lib/test_printf.c with -one or more test cases, if at all feasible. +Thanks +====== +If you add other ``%p`` extensions, please extend ``lib/test_printf.c`` +with one or more test cases, if at all feasible. Thank you for your cooperation and attention. diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 01c3957b2de6..f9247b78e8ef 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1727,115 +1727,73 @@ static char *ptr_to_id(char *buf, char *end, void *ptr, struct printf_spec spec) return number(buf, end, hashval, spec); } +/** + * DOC: Extended Format Pointer Specifiers + * + * Briefly we handle the following extensions: + * + * - ``F`` - For symbolic function descriptor pointers with offset. + * - ``f`` - For simple symbolic function names without offset. + * + * - ``S`` - For symbolic direct pointers with offset. + * - ``s`` - For symbolic direct pointers without offset. + * - ``[FfSs]R`` - As above with ``__builtin_extract_return_addr()`` translation. + * - ``B`` - For backtraced symbolic direct pointers with offset. + * - ``R`` - For decoded struct resource, e.g., [mem 0x0-0x1f 64bit pref]. + * - ``r`` - For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201]. + * - ``b[l]`` - For a bitmap, the number of bits is determined by the field + * width which must be explicitly specified either as part of the format + * string ``32b[l]`` or through ``*b[l]``, ``[l]`` selects range-list format + * instead of hex format. + * - ``M`` - For a 6-byte MAC address, it prints the address in the usual + * colon-separated hex notation. + * - ``m`` - For a 6-byte MAC address, it prints the hex address without colons. + * - ``MF`` - For a 6-byte MAC FDDI address, it prints the address with a + * dash-separated hex notation. + * - ``[mM]R`` - For a 6-byte MAC address, Reverse order (Bluetooth). + * - ``I[46]`` - For IPv4/IPv6 addresses printed in the usual way. + * - ``I[S][pfs]`` - For generic IPv4/IPv6 address (struct sockaddr *) that falls + * back to ``[4]`` or ``[6]`` and is able to print port ``[p]``, + * flowinfo ``[f]``, scope ``[s]``. + * - ``i[46]`` - For 'raw' IPv4/IPv6 addresses IPv6 omits the colons (01020304...0f) + * IPv4 uses dot-separated decimal with leading 0's (010.123.045.006). + * - ``i[S][pfs]`` - For generic IPv4/IPv6 address (struct sockaddr *) that falls back + * to ``[4]`` or ``[6]`` (``[pfs]`` as above). + * - ``[Ii][4S][hnbl]`` - For IPv4 addresses in host, network, big or little endian order. + * - ``I[6S]c`` - For IPv6 addresses printed as per http://tools.ietf.org/html/rfc5952. + * - ``E[achnops]`` - For an escaped buffer. + * - ``U`` - For a 16 byte UUID/GUID. + * - ``V`` - For a ``struct va_format`` which contains a format ``string *`` + * and ``va_list *``. + * - ``K`` - For a kernel pointer that should be hidden from unprivileged users. + * - ``NF`` - For a ``netdev_features_t``. + * - ``h[CDN]`` - For a variable-length buffer. + * - ``a[pd]`` - For address types ``[p] phys_addr_t``, ``[d] dma_addr_t`` and + * derivatives. + * - ``d[234]`` - For a dentry name (optionally 2-4 last components). + * - ``D[234]`` - Same as 'd' but for a struct file. + * - ``g`` - For ``block_device`` name (gendisk + partition number). + * - ``C[n]`` - For a clock, it prints the name (Common Clock Framework) or + * address (legacy clock framework) of the clock. ``[n]`` is optional. + * - ``Cr`` - For a clock, it prints the current rate of the clock. + * - ``G`` - For flags to be printed as a collection of symbolic strings that + * would construct the specific value. + * - ``O`` - For a kobject based struct (device node). + * - ``x`` - For printing the address. Equivalent to ``%lx``. + */ + /* * Show a '%p' thing. A kernel extension is that the '%p' is followed * by an extra set of alphanumeric characters that are extended format * specifiers. * + * Please see Documentation/printk-formats.rst for fuller description + * of specifier extensions. Also please update this file when making + * changes. + * * Please update scripts/checkpatch.pl when adding/removing conversion * characters. (Search for "check for vsprintf extension"). * - * Right now we handle: - * - * - 'F' For symbolic function descriptor pointers with offset - * - 'f' For simple symbolic function names without offset - * - 'S' For symbolic direct pointers with offset - * - 's' For symbolic direct pointers without offset - * - '[FfSs]R' as above with __builtin_extract_return_addr() translation - * - 'B' For backtraced symbolic direct pointers with offset - * - 'R' For decoded struct resource, e.g., [mem 0x0-0x1f 64bit pref] - * - 'r' For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201] - * - 'b[l]' For a bitmap, the number of bits is determined by the field - * width which must be explicitly specified either as part of the - * format string '%32b[l]' or through '%*b[l]', [l] selects - * range-list format instead of hex format - * - 'M' For a 6-byte MAC address, it prints the address in the - * usual colon-separated hex notation - * - 'm' For a 6-byte MAC address, it prints the hex address without colons - * - 'MF' For a 6-byte MAC FDDI address, it prints the address - * with a dash-separated hex notation - * - '[mM]R' For a 6-byte MAC address, Reverse order (Bluetooth) - * - 'I' [46] for IPv4/IPv6 addresses printed in the usual way - * IPv4 uses dot-separated decimal without leading 0's (1.2.3.4) - * IPv6 uses colon separated network-order 16 bit hex with leading 0's - * [S][pfs] - * Generic IPv4/IPv6 address (struct sockaddr *) that falls back to - * [4] or [6] and is able to print port [p], flowinfo [f], scope [s] - * - 'i' [46] for 'raw' IPv4/IPv6 addresses - * IPv6 omits the colons (01020304...0f) - * IPv4 uses dot-separated decimal with leading 0's (010.123.045.006) - * [S][pfs] - * Generic IPv4/IPv6 address (struct sockaddr *) that falls back to - * [4] or [6] and is able to print port [p], flowinfo [f], scope [s] - * - '[Ii][4S][hnbl]' IPv4 addresses in host, network, big or little endian order - * - 'I[6S]c' for IPv6 addresses printed as specified by - * http://tools.ietf.org/html/rfc5952 - * - 'E[achnops]' For an escaped buffer, where rules are defined by combination - * of the following flags (see string_escape_mem() for the - * details): - * a - ESCAPE_ANY - * c - ESCAPE_SPECIAL - * h - ESCAPE_HEX - * n - ESCAPE_NULL - * o - ESCAPE_OCTAL - * p - ESCAPE_NP - * s - ESCAPE_SPACE - * By default ESCAPE_ANY_NP is used. - * - 'U' For a 16 byte UUID/GUID, it prints the UUID/GUID in the form - * "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" - * Options for %pU are: - * b big endian lower case hex (default) - * B big endian UPPER case hex - * l little endian lower case hex - * L little endian UPPER case hex - * big endian output byte order is: - * [0][1][2][3]-[4][5]-[6][7]-[8][9]-[10][11][12][13][14][15] - * little endian output byte order is: - * [3][2][1][0]-[5][4]-[7][6]-[8][9]-[10][11][12][13][14][15] - * - 'V' For a struct va_format which contains a format string * and va_list *, - * call vsnprintf(->format, *->va_list). - * Implements a "recursive vsnprintf". - * Do not use this feature without some mechanism to verify the - * correctness of the format string and va_list arguments. - * - 'K' For a kernel pointer that should be hidden from unprivileged users - * - 'NF' For a netdev_features_t - * - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with - * a certain separator (' ' by default): - * C colon - * D dash - * N no separator - * The maximum supported length is 64 bytes of the input. Consider - * to use print_hex_dump() for the larger input. - * - 'a[pd]' For address types [p] phys_addr_t, [d] dma_addr_t and derivatives - * (default assumed to be phys_addr_t, passed by reference) - * - 'd[234]' For a dentry name (optionally 2-4 last components) - * - 'D[234]' Same as 'd' but for a struct file - * - 'g' For block_device name (gendisk + partition number) - * - 'C' For a clock, it prints the name (Common Clock Framework) or address - * (legacy clock framework) of the clock - * - 'Cn' For a clock, it prints the name (Common Clock Framework) or address - * (legacy clock framework) of the clock - * - 'Cr' For a clock, it prints the current rate of the clock - * - 'G' For flags to be printed as a collection of symbolic strings that would - * construct the specific value. Supported flags given by option: - * p page flags (see struct page) given as pointer to unsigned long - * g gfp flags (GFP_* and __GFP_*) given as pointer to gfp_t - * v vma flags (VM_*) given as pointer to unsigned long - * - 'O' For a kobject based struct. Must be one of the following: - * - 'OF[fnpPcCF]' For a device tree object - * Without any optional arguments prints the full_name - * f device node full_name - * n device node name - * p device node phandle - * P device node path spec (name + @unit) - * F device node flags - * c major compatible string - * C full compatible string - * - * - 'x' For printing the address. Equivalent to "%lx". - * - * ** Please update also Documentation/printk-formats.txt when making changes ** - * * Note: The difference between 'S' and 'F' is that on ia64 and ppc64 * function pointers are really function descriptors, which contain a * pointer to the real address. -- 2.7.4