How is the operating system able to know the battery level?

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Even if we remove the default OS and install a new one it can interact with the battery. Are there some drivers for it? How does it work?










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    Even if we remove the default OS and install a new one it can interact with the battery. Are there some drivers for it? How does it work?










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      Even if we remove the default OS and install a new one it can interact with the battery. Are there some drivers for it? How does it work?










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      Even if we remove the default OS and install a new one it can interact with the battery. Are there some drivers for it? How does it work?







      battery operating-systems






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      Braiam

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          2 Answers
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          active

          oldest

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          up vote
          12
          down vote













          As a complement to the other answer, how does the software running on the computer know what the battery level is? It asks the battery.



          Most laptop batteries are smart batteries that have their own microcontroller or "fuel gauge" ASIC, which the host can communicate with over SMBus. People have reverse engineered some examples.



          The SMBus may or may not be exposed directly to the operating system in a way that allows the administrator to query it directly. There are various programs like OpenHardwareMonitor or Speccy or lm-sensors that can interrogate the bus to find out about the hardware.






          share|improve this answer




















          • great explanation to understand the basic concept in general! Although I would ad quotation marks around the word "asks".
            – Albin
            4 hours ago










          • There is no conflict with my answer : SMBus is a component that is managed by ACPI for mobile computers in which it exists.
            – harrymc
            4 hours ago










          • This smart battery interface can also be exposed through more standard means, such as USB. For instance, many UPSs have a USB port on them that, when plugged into the computer, tells the computer how much power is left and displays it just like a laptop does.
            – TheHansinator
            2 hours ago

















          up vote
          8
          down vote













          The operating system interfaces with the firmware of an embedded controller
          that is part of the
          Advanced Configuration and Power Interface (ACPI).



          Wikipedia defines it as :




          In a computer, the Advanced Configuration and Power Interface (ACPI) provides an open standard that operating systems can use to discover and configure computer hardware components, to perform power management by (for example) putting unused components to sleep, and to perform status monitoring. First released in December 1996, ACPI aims to replace Advanced Power Management (APM), the MultiProcessor Specification, and the Plug and Play BIOS (PnP) Specification.[1] ACPI brings the power management under the control of the operating system, as opposed to the previous BIOS-centric system that relied on platform-specific firmware to determine power management and configuration policies.



          Internally, ACPI advertises the available components and their functions to the operating system kernel using instruction lists ("methods") provided through the system firmware (Unified Extensible Firmware Interface (UEFI) or BIOS), which the kernel parses. ACPI then executes the desired operations (such as the initialization of hardware components) using an embedded minimal virtual machine.




          The answer is then that a circuit or micro-chip is embedded in the motherboard,
          that itself contains a micro operating system which makes available some services
          via the computer firmware - UEFI or BIOS. It controls many aspects of
          power and device management.



          The computer operating system has a system driver that is dedicated to interfacing
          with ACPI. Once ACPI is activated, it takes exclusive control of all aspects of
          power management and device configuration.



          In many aspects ACPI is an operating system behind your operating system,
          except that it comes with the motherboard and is not under your control.
          There have been voices likening it to a Trojan horse and calling it
          a security risk.
          It may be disabled, but some computers may not boot without it,
          and advanced power management is then in any case disabled as well.



          For more information about its use in Windows see the article
          Battery and power subsystem hardware design.






          share|improve this answer
















          • 1




            I might be wrong but it sounds like the last paragraph's description completely confuses ACPI with SMM and/or with Intel's ME/AMT. ACPI is mostly a static data structure, with small amounts of bytecode that the OS itself has to interpret, whereas ME is the actual system.
            – grawity
            5 hours ago







          • 1




            @grawity: Don't think so. You may find a similar discussion in the Wikipedia ACPI article.
            – harrymc
            5 hours ago






          • 1




            I don't see much discussion in there beyond a few quotes from one Shuttleworth's one blog post, and after reading both pages I'm not convinced in the slightest – it seems to me that he just lumps everything that comes with the system under the "ACPI" name, be it the BIOS or the Intel ME or whatever. As far as I know, out of all the garbage that comes with a modern system, ACPI is probably the only part that doesn't run on its own, and certainly not under the OS.
            – grawity
            5 hours ago











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          2 Answers
          2






          active

          oldest

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          2 Answers
          2






          active

          oldest

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          active

          oldest

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          active

          oldest

          votes








          up vote
          12
          down vote













          As a complement to the other answer, how does the software running on the computer know what the battery level is? It asks the battery.



          Most laptop batteries are smart batteries that have their own microcontroller or "fuel gauge" ASIC, which the host can communicate with over SMBus. People have reverse engineered some examples.



          The SMBus may or may not be exposed directly to the operating system in a way that allows the administrator to query it directly. There are various programs like OpenHardwareMonitor or Speccy or lm-sensors that can interrogate the bus to find out about the hardware.






          share|improve this answer




















          • great explanation to understand the basic concept in general! Although I would ad quotation marks around the word "asks".
            – Albin
            4 hours ago










          • There is no conflict with my answer : SMBus is a component that is managed by ACPI for mobile computers in which it exists.
            – harrymc
            4 hours ago










          • This smart battery interface can also be exposed through more standard means, such as USB. For instance, many UPSs have a USB port on them that, when plugged into the computer, tells the computer how much power is left and displays it just like a laptop does.
            – TheHansinator
            2 hours ago














          up vote
          12
          down vote













          As a complement to the other answer, how does the software running on the computer know what the battery level is? It asks the battery.



          Most laptop batteries are smart batteries that have their own microcontroller or "fuel gauge" ASIC, which the host can communicate with over SMBus. People have reverse engineered some examples.



          The SMBus may or may not be exposed directly to the operating system in a way that allows the administrator to query it directly. There are various programs like OpenHardwareMonitor or Speccy or lm-sensors that can interrogate the bus to find out about the hardware.






          share|improve this answer




















          • great explanation to understand the basic concept in general! Although I would ad quotation marks around the word "asks".
            – Albin
            4 hours ago










          • There is no conflict with my answer : SMBus is a component that is managed by ACPI for mobile computers in which it exists.
            – harrymc
            4 hours ago










          • This smart battery interface can also be exposed through more standard means, such as USB. For instance, many UPSs have a USB port on them that, when plugged into the computer, tells the computer how much power is left and displays it just like a laptop does.
            – TheHansinator
            2 hours ago












          up vote
          12
          down vote










          up vote
          12
          down vote









          As a complement to the other answer, how does the software running on the computer know what the battery level is? It asks the battery.



          Most laptop batteries are smart batteries that have their own microcontroller or "fuel gauge" ASIC, which the host can communicate with over SMBus. People have reverse engineered some examples.



          The SMBus may or may not be exposed directly to the operating system in a way that allows the administrator to query it directly. There are various programs like OpenHardwareMonitor or Speccy or lm-sensors that can interrogate the bus to find out about the hardware.






          share|improve this answer












          As a complement to the other answer, how does the software running on the computer know what the battery level is? It asks the battery.



          Most laptop batteries are smart batteries that have their own microcontroller or "fuel gauge" ASIC, which the host can communicate with over SMBus. People have reverse engineered some examples.



          The SMBus may or may not be exposed directly to the operating system in a way that allows the administrator to query it directly. There are various programs like OpenHardwareMonitor or Speccy or lm-sensors that can interrogate the bus to find out about the hardware.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 5 hours ago









          pjc50

          5,0911726




          5,0911726











          • great explanation to understand the basic concept in general! Although I would ad quotation marks around the word "asks".
            – Albin
            4 hours ago










          • There is no conflict with my answer : SMBus is a component that is managed by ACPI for mobile computers in which it exists.
            – harrymc
            4 hours ago










          • This smart battery interface can also be exposed through more standard means, such as USB. For instance, many UPSs have a USB port on them that, when plugged into the computer, tells the computer how much power is left and displays it just like a laptop does.
            – TheHansinator
            2 hours ago
















          • great explanation to understand the basic concept in general! Although I would ad quotation marks around the word "asks".
            – Albin
            4 hours ago










          • There is no conflict with my answer : SMBus is a component that is managed by ACPI for mobile computers in which it exists.
            – harrymc
            4 hours ago










          • This smart battery interface can also be exposed through more standard means, such as USB. For instance, many UPSs have a USB port on them that, when plugged into the computer, tells the computer how much power is left and displays it just like a laptop does.
            – TheHansinator
            2 hours ago















          great explanation to understand the basic concept in general! Although I would ad quotation marks around the word "asks".
          – Albin
          4 hours ago




          great explanation to understand the basic concept in general! Although I would ad quotation marks around the word "asks".
          – Albin
          4 hours ago












          There is no conflict with my answer : SMBus is a component that is managed by ACPI for mobile computers in which it exists.
          – harrymc
          4 hours ago




          There is no conflict with my answer : SMBus is a component that is managed by ACPI for mobile computers in which it exists.
          – harrymc
          4 hours ago












          This smart battery interface can also be exposed through more standard means, such as USB. For instance, many UPSs have a USB port on them that, when plugged into the computer, tells the computer how much power is left and displays it just like a laptop does.
          – TheHansinator
          2 hours ago




          This smart battery interface can also be exposed through more standard means, such as USB. For instance, many UPSs have a USB port on them that, when plugged into the computer, tells the computer how much power is left and displays it just like a laptop does.
          – TheHansinator
          2 hours ago












          up vote
          8
          down vote













          The operating system interfaces with the firmware of an embedded controller
          that is part of the
          Advanced Configuration and Power Interface (ACPI).



          Wikipedia defines it as :




          In a computer, the Advanced Configuration and Power Interface (ACPI) provides an open standard that operating systems can use to discover and configure computer hardware components, to perform power management by (for example) putting unused components to sleep, and to perform status monitoring. First released in December 1996, ACPI aims to replace Advanced Power Management (APM), the MultiProcessor Specification, and the Plug and Play BIOS (PnP) Specification.[1] ACPI brings the power management under the control of the operating system, as opposed to the previous BIOS-centric system that relied on platform-specific firmware to determine power management and configuration policies.



          Internally, ACPI advertises the available components and their functions to the operating system kernel using instruction lists ("methods") provided through the system firmware (Unified Extensible Firmware Interface (UEFI) or BIOS), which the kernel parses. ACPI then executes the desired operations (such as the initialization of hardware components) using an embedded minimal virtual machine.




          The answer is then that a circuit or micro-chip is embedded in the motherboard,
          that itself contains a micro operating system which makes available some services
          via the computer firmware - UEFI or BIOS. It controls many aspects of
          power and device management.



          The computer operating system has a system driver that is dedicated to interfacing
          with ACPI. Once ACPI is activated, it takes exclusive control of all aspects of
          power management and device configuration.



          In many aspects ACPI is an operating system behind your operating system,
          except that it comes with the motherboard and is not under your control.
          There have been voices likening it to a Trojan horse and calling it
          a security risk.
          It may be disabled, but some computers may not boot without it,
          and advanced power management is then in any case disabled as well.



          For more information about its use in Windows see the article
          Battery and power subsystem hardware design.






          share|improve this answer
















          • 1




            I might be wrong but it sounds like the last paragraph's description completely confuses ACPI with SMM and/or with Intel's ME/AMT. ACPI is mostly a static data structure, with small amounts of bytecode that the OS itself has to interpret, whereas ME is the actual system.
            – grawity
            5 hours ago







          • 1




            @grawity: Don't think so. You may find a similar discussion in the Wikipedia ACPI article.
            – harrymc
            5 hours ago






          • 1




            I don't see much discussion in there beyond a few quotes from one Shuttleworth's one blog post, and after reading both pages I'm not convinced in the slightest – it seems to me that he just lumps everything that comes with the system under the "ACPI" name, be it the BIOS or the Intel ME or whatever. As far as I know, out of all the garbage that comes with a modern system, ACPI is probably the only part that doesn't run on its own, and certainly not under the OS.
            – grawity
            5 hours ago















          up vote
          8
          down vote













          The operating system interfaces with the firmware of an embedded controller
          that is part of the
          Advanced Configuration and Power Interface (ACPI).



          Wikipedia defines it as :




          In a computer, the Advanced Configuration and Power Interface (ACPI) provides an open standard that operating systems can use to discover and configure computer hardware components, to perform power management by (for example) putting unused components to sleep, and to perform status monitoring. First released in December 1996, ACPI aims to replace Advanced Power Management (APM), the MultiProcessor Specification, and the Plug and Play BIOS (PnP) Specification.[1] ACPI brings the power management under the control of the operating system, as opposed to the previous BIOS-centric system that relied on platform-specific firmware to determine power management and configuration policies.



          Internally, ACPI advertises the available components and their functions to the operating system kernel using instruction lists ("methods") provided through the system firmware (Unified Extensible Firmware Interface (UEFI) or BIOS), which the kernel parses. ACPI then executes the desired operations (such as the initialization of hardware components) using an embedded minimal virtual machine.




          The answer is then that a circuit or micro-chip is embedded in the motherboard,
          that itself contains a micro operating system which makes available some services
          via the computer firmware - UEFI or BIOS. It controls many aspects of
          power and device management.



          The computer operating system has a system driver that is dedicated to interfacing
          with ACPI. Once ACPI is activated, it takes exclusive control of all aspects of
          power management and device configuration.



          In many aspects ACPI is an operating system behind your operating system,
          except that it comes with the motherboard and is not under your control.
          There have been voices likening it to a Trojan horse and calling it
          a security risk.
          It may be disabled, but some computers may not boot without it,
          and advanced power management is then in any case disabled as well.



          For more information about its use in Windows see the article
          Battery and power subsystem hardware design.






          share|improve this answer
















          • 1




            I might be wrong but it sounds like the last paragraph's description completely confuses ACPI with SMM and/or with Intel's ME/AMT. ACPI is mostly a static data structure, with small amounts of bytecode that the OS itself has to interpret, whereas ME is the actual system.
            – grawity
            5 hours ago







          • 1




            @grawity: Don't think so. You may find a similar discussion in the Wikipedia ACPI article.
            – harrymc
            5 hours ago






          • 1




            I don't see much discussion in there beyond a few quotes from one Shuttleworth's one blog post, and after reading both pages I'm not convinced in the slightest – it seems to me that he just lumps everything that comes with the system under the "ACPI" name, be it the BIOS or the Intel ME or whatever. As far as I know, out of all the garbage that comes with a modern system, ACPI is probably the only part that doesn't run on its own, and certainly not under the OS.
            – grawity
            5 hours ago













          up vote
          8
          down vote










          up vote
          8
          down vote









          The operating system interfaces with the firmware of an embedded controller
          that is part of the
          Advanced Configuration and Power Interface (ACPI).



          Wikipedia defines it as :




          In a computer, the Advanced Configuration and Power Interface (ACPI) provides an open standard that operating systems can use to discover and configure computer hardware components, to perform power management by (for example) putting unused components to sleep, and to perform status monitoring. First released in December 1996, ACPI aims to replace Advanced Power Management (APM), the MultiProcessor Specification, and the Plug and Play BIOS (PnP) Specification.[1] ACPI brings the power management under the control of the operating system, as opposed to the previous BIOS-centric system that relied on platform-specific firmware to determine power management and configuration policies.



          Internally, ACPI advertises the available components and their functions to the operating system kernel using instruction lists ("methods") provided through the system firmware (Unified Extensible Firmware Interface (UEFI) or BIOS), which the kernel parses. ACPI then executes the desired operations (such as the initialization of hardware components) using an embedded minimal virtual machine.




          The answer is then that a circuit or micro-chip is embedded in the motherboard,
          that itself contains a micro operating system which makes available some services
          via the computer firmware - UEFI or BIOS. It controls many aspects of
          power and device management.



          The computer operating system has a system driver that is dedicated to interfacing
          with ACPI. Once ACPI is activated, it takes exclusive control of all aspects of
          power management and device configuration.



          In many aspects ACPI is an operating system behind your operating system,
          except that it comes with the motherboard and is not under your control.
          There have been voices likening it to a Trojan horse and calling it
          a security risk.
          It may be disabled, but some computers may not boot without it,
          and advanced power management is then in any case disabled as well.



          For more information about its use in Windows see the article
          Battery and power subsystem hardware design.






          share|improve this answer












          The operating system interfaces with the firmware of an embedded controller
          that is part of the
          Advanced Configuration and Power Interface (ACPI).



          Wikipedia defines it as :




          In a computer, the Advanced Configuration and Power Interface (ACPI) provides an open standard that operating systems can use to discover and configure computer hardware components, to perform power management by (for example) putting unused components to sleep, and to perform status monitoring. First released in December 1996, ACPI aims to replace Advanced Power Management (APM), the MultiProcessor Specification, and the Plug and Play BIOS (PnP) Specification.[1] ACPI brings the power management under the control of the operating system, as opposed to the previous BIOS-centric system that relied on platform-specific firmware to determine power management and configuration policies.



          Internally, ACPI advertises the available components and their functions to the operating system kernel using instruction lists ("methods") provided through the system firmware (Unified Extensible Firmware Interface (UEFI) or BIOS), which the kernel parses. ACPI then executes the desired operations (such as the initialization of hardware components) using an embedded minimal virtual machine.




          The answer is then that a circuit or micro-chip is embedded in the motherboard,
          that itself contains a micro operating system which makes available some services
          via the computer firmware - UEFI or BIOS. It controls many aspects of
          power and device management.



          The computer operating system has a system driver that is dedicated to interfacing
          with ACPI. Once ACPI is activated, it takes exclusive control of all aspects of
          power management and device configuration.



          In many aspects ACPI is an operating system behind your operating system,
          except that it comes with the motherboard and is not under your control.
          There have been voices likening it to a Trojan horse and calling it
          a security risk.
          It may be disabled, but some computers may not boot without it,
          and advanced power management is then in any case disabled as well.



          For more information about its use in Windows see the article
          Battery and power subsystem hardware design.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 5 hours ago









          harrymc

          240k10250532




          240k10250532







          • 1




            I might be wrong but it sounds like the last paragraph's description completely confuses ACPI with SMM and/or with Intel's ME/AMT. ACPI is mostly a static data structure, with small amounts of bytecode that the OS itself has to interpret, whereas ME is the actual system.
            – grawity
            5 hours ago







          • 1




            @grawity: Don't think so. You may find a similar discussion in the Wikipedia ACPI article.
            – harrymc
            5 hours ago






          • 1




            I don't see much discussion in there beyond a few quotes from one Shuttleworth's one blog post, and after reading both pages I'm not convinced in the slightest – it seems to me that he just lumps everything that comes with the system under the "ACPI" name, be it the BIOS or the Intel ME or whatever. As far as I know, out of all the garbage that comes with a modern system, ACPI is probably the only part that doesn't run on its own, and certainly not under the OS.
            – grawity
            5 hours ago













          • 1




            I might be wrong but it sounds like the last paragraph's description completely confuses ACPI with SMM and/or with Intel's ME/AMT. ACPI is mostly a static data structure, with small amounts of bytecode that the OS itself has to interpret, whereas ME is the actual system.
            – grawity
            5 hours ago







          • 1




            @grawity: Don't think so. You may find a similar discussion in the Wikipedia ACPI article.
            – harrymc
            5 hours ago






          • 1




            I don't see much discussion in there beyond a few quotes from one Shuttleworth's one blog post, and after reading both pages I'm not convinced in the slightest – it seems to me that he just lumps everything that comes with the system under the "ACPI" name, be it the BIOS or the Intel ME or whatever. As far as I know, out of all the garbage that comes with a modern system, ACPI is probably the only part that doesn't run on its own, and certainly not under the OS.
            – grawity
            5 hours ago








          1




          1




          I might be wrong but it sounds like the last paragraph's description completely confuses ACPI with SMM and/or with Intel's ME/AMT. ACPI is mostly a static data structure, with small amounts of bytecode that the OS itself has to interpret, whereas ME is the actual system.
          – grawity
          5 hours ago





          I might be wrong but it sounds like the last paragraph's description completely confuses ACPI with SMM and/or with Intel's ME/AMT. ACPI is mostly a static data structure, with small amounts of bytecode that the OS itself has to interpret, whereas ME is the actual system.
          – grawity
          5 hours ago





          1




          1




          @grawity: Don't think so. You may find a similar discussion in the Wikipedia ACPI article.
          – harrymc
          5 hours ago




          @grawity: Don't think so. You may find a similar discussion in the Wikipedia ACPI article.
          – harrymc
          5 hours ago




          1




          1




          I don't see much discussion in there beyond a few quotes from one Shuttleworth's one blog post, and after reading both pages I'm not convinced in the slightest – it seems to me that he just lumps everything that comes with the system under the "ACPI" name, be it the BIOS or the Intel ME or whatever. As far as I know, out of all the garbage that comes with a modern system, ACPI is probably the only part that doesn't run on its own, and certainly not under the OS.
          – grawity
          5 hours ago





          I don't see much discussion in there beyond a few quotes from one Shuttleworth's one blog post, and after reading both pages I'm not convinced in the slightest – it seems to me that he just lumps everything that comes with the system under the "ACPI" name, be it the BIOS or the Intel ME or whatever. As far as I know, out of all the garbage that comes with a modern system, ACPI is probably the only part that doesn't run on its own, and certainly not under the OS.
          – grawity
          5 hours ago











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