diff options
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/block/biodoc.txt | 19 | ||||
-rw-r--r-- | Documentation/driver-model/platform.txt | 59 | ||||
-rw-r--r-- | Documentation/filesystems/pohmelfs/design_notes.txt | 5 | ||||
-rw-r--r-- | Documentation/filesystems/pohmelfs/info.txt | 21 | ||||
-rw-r--r-- | Documentation/filesystems/vfs.txt | 3 | ||||
-rw-r--r-- | Documentation/kbuild/makefiles.txt | 10 | ||||
-rw-r--r-- | Documentation/kernel-parameters.txt | 78 | ||||
-rw-r--r-- | Documentation/lguest/.gitignore | 1 | ||||
-rw-r--r-- | Documentation/lguest/lguest.txt | 11 | ||||
-rw-r--r-- | Documentation/networking/bonding.txt | 2 | ||||
-rw-r--r-- | Documentation/sound/alsa/HD-Audio.txt | 4 | ||||
-rw-r--r-- | Documentation/spi/spi-summary | 6 |
12 files changed, 170 insertions, 49 deletions
diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt index ecad6ee..6fab97e 100644 --- a/Documentation/block/biodoc.txt +++ b/Documentation/block/biodoc.txt @@ -1040,23 +1040,21 @@ Front merges are handled by the binary trees in AS and deadline schedulers. iii. Plugging the queue to batch requests in anticipation of opportunities for merge/sort optimizations -This is just the same as in 2.4 so far, though per-device unplugging -support is anticipated for 2.5. Also with a priority-based i/o scheduler, -such decisions could be based on request priorities. - Plugging is an approach that the current i/o scheduling algorithm resorts to so that it collects up enough requests in the queue to be able to take advantage of the sorting/merging logic in the elevator. If the queue is empty when a request comes in, then it plugs the request queue -(sort of like plugging the bottom of a vessel to get fluid to build up) +(sort of like plugging the bath tub of a vessel to get fluid to build up) till it fills up with a few more requests, before starting to service the requests. This provides an opportunity to merge/sort the requests before passing them down to the device. There are various conditions when the queue is unplugged (to open up the flow again), either through a scheduled task or could be on demand. For example wait_on_buffer sets the unplugging going -(by running tq_disk) so the read gets satisfied soon. So in the read case, -the queue gets explicitly unplugged as part of waiting for completion, -in fact all queues get unplugged as a side-effect. +through sync_buffer() running blk_run_address_space(mapping). Or the caller +can do it explicity through blk_unplug(bdev). So in the read case, +the queue gets explicitly unplugged as part of waiting for completion on that +buffer. For page driven IO, the address space ->sync_page() takes care of +doing the blk_run_address_space(). Aside: This is kind of controversial territory, as it's not clear if plugging is @@ -1067,11 +1065,6 @@ Aside: multi-page bios being queued in one shot, we may not need to wait to merge a big request from the broken up pieces coming by. - Per-queue granularity unplugging (still a Todo) may help reduce some of the - concerns with just a single tq_disk flush approach. Something like - blk_kick_queue() to unplug a specific queue (right away ?) - or optionally, all queues, is in the plan. - 4.4 I/O contexts I/O contexts provide a dynamically allocated per process data area. They may be used in I/O schedulers, and in the block layer (could be used for IO statis, diff --git a/Documentation/driver-model/platform.txt b/Documentation/driver-model/platform.txt index 83009fdc..2e2c2ea 100644 --- a/Documentation/driver-model/platform.txt +++ b/Documentation/driver-model/platform.txt @@ -169,3 +169,62 @@ three different ways to find such a match: be probed later if another device registers. (Which is OK, since this interface is only for use with non-hotpluggable devices.) + +Early Platform Devices and Drivers +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The early platform interfaces provide platform data to platform device +drivers early on during the system boot. The code is built on top of the +early_param() command line parsing and can be executed very early on. + +Example: "earlyprintk" class early serial console in 6 steps + +1. Registering early platform device data +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The architecture code registers platform device data using the function +early_platform_add_devices(). In the case of early serial console this +should be hardware configuration for the serial port. Devices registered +at this point will later on be matched against early platform drivers. + +2. Parsing kernel command line +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The architecture code calls parse_early_param() to parse the kernel +command line. This will execute all matching early_param() callbacks. +User specified early platform devices will be registered at this point. +For the early serial console case the user can specify port on the +kernel command line as "earlyprintk=serial.0" where "earlyprintk" is +the class string, "serial" is the name of the platfrom driver and +0 is the platform device id. If the id is -1 then the dot and the +id can be omitted. + +3. Installing early platform drivers belonging to a certain class +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The architecture code may optionally force registration of all early +platform drivers belonging to a certain class using the function +early_platform_driver_register_all(). User specified devices from +step 2 have priority over these. This step is omitted by the serial +driver example since the early serial driver code should be disabled +unless the user has specified port on the kernel command line. + +4. Early platform driver registration +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Compiled-in platform drivers making use of early_platform_init() are +automatically registered during step 2 or 3. The serial driver example +should use early_platform_init("earlyprintk", &platform_driver). + +5. Probing of early platform drivers belonging to a certain class +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The architecture code calls early_platform_driver_probe() to match +registered early platform devices associated with a certain class with +registered early platform drivers. Matched devices will get probed(). +This step can be executed at any point during the early boot. As soon +as possible may be good for the serial port case. + +6. Inside the early platform driver probe() +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The driver code needs to take special care during early boot, especially +when it comes to memory allocation and interrupt registration. The code +in the probe() function can use is_early_platform_device() to check if +it is called at early platform device or at the regular platform device +time. The early serial driver performs register_console() at this point. + +For further information, see <linux/platform_device.h>. diff --git a/Documentation/filesystems/pohmelfs/design_notes.txt b/Documentation/filesystems/pohmelfs/design_notes.txt index 6d6db60..dcf8335 100644 --- a/Documentation/filesystems/pohmelfs/design_notes.txt +++ b/Documentation/filesystems/pohmelfs/design_notes.txt @@ -56,9 +56,10 @@ workloads and can fully utilize the bandwidth to the servers when doing bulk data transfers. POHMELFS clients operate with a working set of servers and are capable of balancing read-only -operations (like lookups or directory listings) between them. +operations (like lookups or directory listings) between them according to IO priorities. Administrators can add or remove servers from the set at run-time via special commands (described -in Documentation/pohmelfs/info.txt file). Writes are replicated to all servers. +in Documentation/pohmelfs/info.txt file). Writes are replicated to all servers, which are connected +with write permission turned on. IO priority and permissions can be changed in run-time. POHMELFS is capable of full data channel encryption and/or strong crypto hashing. One can select any kernel supported cipher, encryption mode, hash type and operation mode diff --git a/Documentation/filesystems/pohmelfs/info.txt b/Documentation/filesystems/pohmelfs/info.txt index 4e3d501..db2e413 100644 --- a/Documentation/filesystems/pohmelfs/info.txt +++ b/Documentation/filesystems/pohmelfs/info.txt @@ -1,6 +1,8 @@ POHMELFS usage information. -Mount options: +Mount options. +All but index, number of crypto threads and maximum IO size can changed via remount. + idx=%u Each mountpoint is associated with a special index via this option. Administrator can add or remove servers from the given index, so all mounts, @@ -52,16 +54,27 @@ mcache_timeout=%u Usage examples. -Add (or remove if it already exists) server server1.net:1025 into the working set with index $idx +Add server server1.net:1025 into the working set with index $idx with appropriate hash algorithm and key file and cipher algorithm, mode and key file: -$cfg -a server1.net -p 1025 -i $idx -K $hash_key -k $cipher_key +$cfg A add -a server1.net -p 1025 -i $idx -K $hash_key -k $cipher_key Mount filesystem with given index $idx to /mnt mountpoint. Client will connect to all servers specified in the working set via previous command: mount -t pohmel -o idx=$idx q /mnt -One can add or remove servers from working set after mounting too. +Change permissions to read-only (-I 1 option, '-I 2' - write-only, 3 - rw): +$cfg A modify -a server1.net -p 1025 -i $idx -I 1 + +Change IO priority to 123 (node with the highest priority gets read requests). +$cfg A modify -a server1.net -p 1025 -i $idx -P 123 +One can check currect status of all connections in the mountstats file: +# cat /proc/$PID/mountstats +... +device none mounted on /mnt with fstype pohmel +idx addr(:port) socket_type protocol active priority permissions +0 server1.net:1026 1 6 1 250 1 +0 server2.net:1025 1 6 1 123 3 Server installation. diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index deeeed0..f49eecf 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -277,8 +277,7 @@ or bottom half). unfreeze_fs: called when VFS is unlocking a filesystem and making it writable again. - statfs: called when the VFS needs to get filesystem statistics. This - is called with the kernel lock held + statfs: called when the VFS needs to get filesystem statistics. remount_fs: called when the filesystem is remounted. This is called with the kernel lock held diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index d4b0567..d76cfd8 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -316,6 +316,16 @@ more details, with real examples. #arch/m68k/fpsp040/Makefile ldflags-y := -x + subdir-ccflags-y, subdir-asflags-y + The two flags listed above are similar to ccflags-y and as-falgs-y. + The difference is that the subdir- variants has effect for the kbuild + file where tey are present and all subdirectories. + Options specified using subdir-* are added to the commandline before + the options specified using the non-subdir variants. + + Example: + subdir-ccflags-y := -Werror + CFLAGS_$@, AFLAGS_$@ CFLAGS_$@ and AFLAGS_$@ only apply to commands in current diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 6172e43..600cdd7 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -134,7 +134,7 @@ and is between 256 and 4096 characters. It is defined in the file ./include/asm/setup.h as COMMAND_LINE_SIZE. - acpi= [HW,ACPI,X86-64,i386] + acpi= [HW,ACPI,X86] Advanced Configuration and Power Interface Format: { force | off | ht | strict | noirq | rsdt } force -- enable ACPI if default was off @@ -218,7 +218,7 @@ and is between 256 and 4096 characters. It is defined in the file acpi_osi="!string2" # remove built-in string2 acpi_osi= # disable all strings - acpi_pm_good [X86-32,X86-64] + acpi_pm_good [X86] Override the pmtimer bug detection: force the kernel to assume that this machine's pmtimer latches its value and always returns good values. @@ -231,6 +231,35 @@ and is between 256 and 4096 characters. It is defined in the file power state again in power transition. 1 : disable the power state check + acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode + Format: { level | edge | high | low } + + acpi_serialize [HW,ACPI] force serialization of AML methods + + acpi_skip_timer_override [HW,ACPI] + Recognize and ignore IRQ0/pin2 Interrupt Override. + For broken nForce2 BIOS resulting in XT-PIC timer. + + acpi_sleep= [HW,ACPI] Sleep options + Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, + old_ordering, s4_nonvs } + See Documentation/power/video.txt for information on + s3_bios and s3_mode. + s3_beep is for debugging; it makes the PC's speaker beep + as soon as the kernel's real-mode entry point is called. + s4_nohwsig prevents ACPI hardware signature from being + used during resume from hibernation. + old_ordering causes the ACPI 1.0 ordering of the _PTS + control method, with respect to putting devices into + low power states, to be enforced (the ACPI 2.0 ordering + of _PTS is used by default). + s4_nonvs prevents the kernel from saving/restoring the + ACPI NVS memory during hibernation. + + acpi_use_timer_override [HW,ACPI] + Use timer override. For some broken Nvidia NF5 boards + that require a timer override, but don't have HPET + acpi_enforce_resources= [ACPI] { strict | lax | no } Check for resource conflicts between native drivers @@ -250,6 +279,9 @@ and is between 256 and 4096 characters. It is defined in the file ad1848= [HW,OSS] Format: <io>,<irq>,<dma>,<dma2>,<type> + add_efi_memmap [EFI; X86] Include EFI memory map in + kernel's map of available physical RAM. + advansys= [HW,SCSI] See header of drivers/scsi/advansys.c. @@ -459,7 +491,7 @@ and is between 256 and 4096 characters. It is defined in the file Also note the kernel might malfunction if you disable some critical bits. - code_bytes [IA32/X86_64] How many bytes of object code to print + code_bytes [X86] How many bytes of object code to print in an oops report. Range: 0 - 8192 Default: 64 @@ -592,7 +624,7 @@ and is between 256 and 4096 characters. It is defined in the file MTRR settings. This parameter disables that behavior, possibly causing your machine to run very slowly. - disable_timer_pin_1 [i386,x86-64] + disable_timer_pin_1 [X86] Disable PIN 1 of APIC timer Can be useful to work around chipset bugs. @@ -624,7 +656,7 @@ and is between 256 and 4096 characters. It is defined in the file UART at the specified I/O port or MMIO address. The options are the same as for ttyS, above. - earlyprintk= [X86-32,X86-64,SH,BLACKFIN] + earlyprintk= [X86,SH,BLACKFIN] earlyprintk=vga earlyprintk=serial[,ttySn[,baudrate]] earlyprintk=dbgp @@ -659,7 +691,7 @@ and is between 256 and 4096 characters. It is defined in the file See Documentation/block/as-iosched.txt and Documentation/block/deadline-iosched.txt for details. - elfcorehdr= [IA64,PPC,SH,X86-32,X86_64] + elfcorehdr= [IA64,PPC,SH,X86] Specifies physical address of start of kernel core image elf header. Generally kexec loader will pass this option to capture kernel. @@ -938,7 +970,7 @@ and is between 256 and 4096 characters. It is defined in the file See comment before marvel_specify_io7 in arch/alpha/kernel/core_marvel.c. - io_delay= [X86-32,X86-64] I/O delay method + io_delay= [X86] I/O delay method 0x80 Standard port 0x80 based delay 0xed @@ -1000,7 +1032,7 @@ and is between 256 and 4096 characters. It is defined in the file keepinitrd [HW,ARM] - kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter + kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter specifies the amount of memory usable by the kernel for non-movable allocations. The requested amount is spread evenly throughout all nodes in the system. The @@ -1034,7 +1066,7 @@ and is between 256 and 4096 characters. It is defined in the file Configure the RouterBoard 532 series on-chip Ethernet adapter MAC address. - kstack=N [X86-32,X86-64] Print N words from the kernel stack + kstack=N [X86] Print N words from the kernel stack in oops dumps. l2cr= [PPC] @@ -1044,7 +1076,7 @@ and is between 256 and 4096 characters. It is defined in the file lapic [X86-32,APIC] Enable the local APIC even if BIOS disabled it. - lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer + lapic_timer_c2_ok [X86,APIC] trust the local apic timer in C2 power state. libata.dma= [LIBATA] DMA control @@ -1229,7 +1261,7 @@ and is between 256 and 4096 characters. It is defined in the file [KNL,SH] Allow user to override the default size for per-device physically contiguous DMA buffers. - memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact + memmap=exactmap [KNL,X86] Enable setting of an exact E820 memory map, as specified by the user. Such memmap=exactmap lines can be constructed based on BIOS output or other requirements. See the memmap=nn@ss @@ -1320,7 +1352,7 @@ and is between 256 and 4096 characters. It is defined in the file mousedev.yres= [MOUSE] Vertical screen resolution, used for devices reporting absolute coordinates, such as tablets - movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter + movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter is similar to kernelcore except it specifies the amount of memory used for migratable allocations. If both kernelcore and movablecore is specified, @@ -1422,7 +1454,7 @@ and is between 256 and 4096 characters. It is defined in the file when a NMI is triggered. Format: [state][,regs][,debounce][,die] - nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels + nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels Format: [panic,][num] Valid num: 0,1,2 0 - turn nmi_watchdog off @@ -1475,11 +1507,11 @@ and is between 256 and 4096 characters. It is defined in the file nodsp [SH] Disable hardware DSP at boot time. - noefi [X86-32,X86-64] Disable EFI runtime services support. + noefi [X86] Disable EFI runtime services support. noexec [IA-64] - noexec [X86-32,X86-64] + noexec [X86] On X86-32 available only on PAE configured kernels. noexec=on: enable non-executable mappings (default) noexec=off: disable non-executable mappings @@ -1525,7 +1557,7 @@ and is between 256 and 4096 characters. It is defined in the file noirqdebug [X86-32] Disables the code which attempts to detect and disable unhandled interrupt sources. - no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for + no_timer_check [X86,APIC] Disables the code which tests for broken timer IRQ sources. noisapnp [ISAPNP] Disables ISA PnP code. @@ -1689,7 +1721,7 @@ and is between 256 and 4096 characters. It is defined in the file disable the use of PCIE advanced error reporting. nodomains [PCI] Disable support for multiple PCI root domains (aka PCI segments, in ACPI-speak). - nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI + nommconf [X86] Disable use of MMCONFIG for PCI Configuration nomsi [MSI] If the PCI_MSI kernel config parameter is enabled, this kernel boot option can be used to @@ -1838,6 +1870,12 @@ and is between 256 and 4096 characters. It is defined in the file autoconfiguration. Ranges are in pairs (memory base and size). + ports= [IP_VS_FTP] IPVS ftp helper module + Default is 21. + Up to 8 (IP_VS_APP_MAX_PORTS) ports + may be specified. + Format: <port>,<port>.... + print-fatal-signals= [KNL] debug: print fatal signals print-fatal-signals=1: print segfault info to @@ -2380,7 +2418,7 @@ and is between 256 and 4096 characters. It is defined in the file reported either. unknown_nmi_panic - [X86-32,X86-64] + [X86] Set unknown_nmi_panic=1 early on boot. usbcore.autosuspend= @@ -2447,12 +2485,12 @@ and is between 256 and 4096 characters. It is defined in the file medium is write-protected). Example: quirks=0419:aaf5:rl,0421:0433:rc - vdso= [X86-32,SH,x86-64] + vdso= [X86,SH] vdso=2: enable compat VDSO (default with COMPAT_VDSO) vdso=1: enable VDSO (default) vdso=0: disable VDSO mapping - vdso32= [X86-32,X86-64] + vdso32= [X86] vdso32=2: enable compat VDSO (default with COMPAT_VDSO) vdso32=1: enable 32-bit VDSO (default) vdso32=0: disable 32-bit VDSO mapping diff --git a/Documentation/lguest/.gitignore b/Documentation/lguest/.gitignore new file mode 100644 index 0000000..115587f --- /dev/null +++ b/Documentation/lguest/.gitignore @@ -0,0 +1 @@ +lguest diff --git a/Documentation/lguest/lguest.txt b/Documentation/lguest/lguest.txt index 29510dc..28c7473 100644 --- a/Documentation/lguest/lguest.txt +++ b/Documentation/lguest/lguest.txt @@ -3,11 +3,11 @@ /, /` - or, A Young Coder's Illustrated Hypervisor \\"--\\ http://lguest.ozlabs.org -Lguest is designed to be a minimal hypervisor for the Linux kernel, for -Linux developers and users to experiment with virtualization with the -minimum of complexity. Nonetheless, it should have sufficient -features to make it useful for specific tasks, and, of course, you are -encouraged to fork and enhance it (see drivers/lguest/README). +Lguest is designed to be a minimal 32-bit x86 hypervisor for the Linux kernel, +for Linux developers and users to experiment with virtualization with the +minimum of complexity. Nonetheless, it should have sufficient features to +make it useful for specific tasks, and, of course, you are encouraged to fork +and enhance it (see drivers/lguest/README). Features: @@ -37,6 +37,7 @@ Running Lguest: "Paravirtualized guest support" = Y "Lguest guest support" = Y "High Memory Support" = off/4GB + "PAE (Physical Address Extension) Support" = N "Alignment value to which kernel should be aligned" = 0x100000 (CONFIG_PARAVIRT=y, CONFIG_LGUEST_GUEST=y, CONFIG_HIGHMEM64G=n and CONFIG_PHYSICAL_ALIGN=0x100000) diff --git a/Documentation/networking/bonding.txt b/Documentation/networking/bonding.txt index 5ede747..0876275 100644 --- a/Documentation/networking/bonding.txt +++ b/Documentation/networking/bonding.txt @@ -1242,7 +1242,7 @@ monitoring is enabled, and vice-versa. To add ARP targets: # echo +192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target # echo +192.168.0.101 > /sys/class/net/bond0/bonding/arp_ip_target - NOTE: up to 10 target addresses may be specified. + NOTE: up to 16 target addresses may be specified. To remove an ARP target: # echo -192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target diff --git a/Documentation/sound/alsa/HD-Audio.txt b/Documentation/sound/alsa/HD-Audio.txt index c5948f2..88b7433 100644 --- a/Documentation/sound/alsa/HD-Audio.txt +++ b/Documentation/sound/alsa/HD-Audio.txt @@ -169,7 +169,7 @@ PCI SSID look-up. What `model` option values are available depends on the codec chip. Check your codec chip from the codec proc file (see "Codec Proc-File" section below). It will show the vendor/product name of your codec -chip. Then, see Documentation/sound/alsa/HD-Audio-Modelstxt file, +chip. Then, see Documentation/sound/alsa/HD-Audio-Models.txt file, the section of HD-audio driver. You can find a list of codecs and `model` options belonging to each codec. For example, for Realtek ALC262 codec chip, pass `model=ultra` for devices that are compatible @@ -177,7 +177,7 @@ with Samsung Q1 Ultra. Thus, the first thing you can do for any brand-new, unsupported and non-working HD-audio hardware is to check HD-audio codec and several -different `model` option values. If you have a luck, some of them +different `model` option values. If you have any luck, some of them might suit with your device well. Some codecs such as ALC880 have a special model option `model=test`. diff --git a/Documentation/spi/spi-summary b/Documentation/spi/spi-summary index 0f5122e..4a02d25 100644 --- a/Documentation/spi/spi-summary +++ b/Documentation/spi/spi-summary @@ -511,10 +511,16 @@ SPI MASTER METHODS This sets up the device clock rate, SPI mode, and word sizes. Drivers may change the defaults provided by board_info, and then call spi_setup(spi) to invoke this routine. It may sleep. + Unless each SPI slave has its own configuration registers, don't change them right away ... otherwise drivers could corrupt I/O that's in progress for other SPI devices. + ** BUG ALERT: for some reason the first version of + ** many spi_master drivers seems to get this wrong. + ** When you code setup(), ASSUME that the controller + ** is actively processing transfers for another device. + master->transfer(struct spi_device *spi, struct spi_message *message) This must not sleep. Its responsibility is arrange that the transfer happens and its complete() callback is issued. The two |