diff options
Diffstat (limited to 'docs/specs/acpi_nvdimm.txt')
| -rw-r--r-- | docs/specs/acpi_nvdimm.txt | 99 |
1 files changed, 51 insertions, 48 deletions
diff --git a/docs/specs/acpi_nvdimm.txt b/docs/specs/acpi_nvdimm.txt index 4aa5e3de29..3f322e6f55 100644 --- a/docs/specs/acpi_nvdimm.txt +++ b/docs/specs/acpi_nvdimm.txt @@ -65,8 +65,8 @@ _FIT(Firmware Interface Table) The detailed definition of the structure can be found at ACPI 6.0: 5.2.25 NVDIMM Firmware Interface Table (NFIT). -QEMU NVDIMM Implemention -======================== +QEMU NVDIMM Implementation +========================== QEMU uses 4 bytes IO Port starting from 0x0a18 and a RAM-based memory page for NVDIMM ACPI. @@ -80,8 +80,17 @@ Memory: emulates _DSM access and writes the output data to it. ACPI writes _DSM Input Data (based on the offset in the page): - [0x0 - 0x3]: 4 bytes, NVDIMM Device Handle, 0 is reserved for NVDIMM - Root device. + [0x0 - 0x3]: 4 bytes, NVDIMM Device Handle. + + The handle is completely QEMU internal thing, the values in + range [1, 0xFFFF] indicate nvdimm device. Other values are + reserved for other purposes. + + Reserved handles: + 0 is reserved for nvdimm root device named NVDR. + 0x10000 is reserved for QEMU internal DSM function called on + the root device. + [0x4 - 0x7]: 4 bytes, Revision ID, that is the Arg1 of _DSM method. [0x8 - 0xB]: 4 bytes. Function Index, that is the Arg2 of _DSM method. [0xC - 0xFFF]: 4084 bytes, the Arg3 of _DSM method. @@ -127,28 +136,17 @@ _DSM process diagram: | result from the page | | | +--------------------------+ +--------------+ -Device Handle Reservation -------------------------- -As we mentioned above, byte 0 ~ byte 3 in the DSM memory save NVDIMM device -handle. The handle is completely QEMU internal thing, the values in range -[0, 0xFFFF] indicate nvdimm device (O means nvdimm root device named NVDR), -other values are reserved by other purpose. - -Current reserved handle: -0x10000 is reserved for QEMU internal DSM function called on the root -device. +NVDIMM hotplug +-------------- +ACPI BIOS GPE.4 handler is dedicated for notifying OS about nvdimm device +hot-add event. QEMU internal use only _DSM function ------------------------------------ -UUID, 648B9CF2-CDA1-4312-8AD9-49C4AF32BD62, is reserved for QEMU internal -DSM function. - -There is the function introduced by QEMU and only used by QEMU internal. - 1) Read FIT - As we only reserved one page for NVDIMM ACPI it is impossible to map the - whole FIT data to guest's address space. This function is used by _FIT - method to read a piece of FIT data from QEMU. + _FIT method uses _DSM method to fetch NFIT structures blob from QEMU + in 1 page sized increments which are then concatenated and returned + as _FIT method result. Input parameters: Arg0 – UUID {set to 648B9CF2-CDA1-4312-8AD9-49C4AF32BD62} @@ -156,29 +154,34 @@ There is the function introduced by QEMU and only used by QEMU internal. Arg2 - Function Index, 0x1 Arg3 - A package containing a buffer whose layout is as follows: - +----------+-------------+-------------+-----------------------------------+ - | Filed | Byte Length | Byte Offset | Description | - +----------+-------------+-------------+-----------------------------------+ - | offset | 4 | 0 | the offset of FIT buffer | - +----------+-------------+-------------+-----------------------------------+ - - Output: - +----------+-------------+-------------+-----------------------------------+ - | Filed | Byte Length | Byte Offset | Description | - +----------+-------------+-------------+-----------------------------------+ - | | | | return status codes | - | | | | 0x100 indicates fit has been | - | status | 4 | 0 | updated | - | | | | other follows Chapter 3 in DSM | - | | | | Spec Rev1 | - +----------+-------------+-------------+-----------------------------------+ - | fit data | Varies | 4 | FIT data | - | | | | | - +----------+-------------+-------------+-----------------------------------+ - - The FIT offset is maintained by the caller itself, current offset plugs - the length returned by the function is the next offset we should read. - When all the FIT data has been read out, zero length is returned. - - If it returns 0x100, OSPM should restart to read FIT (read from offset 0 - again). + +----------+--------+--------+-------------------------------------------+ + | Field | Length | Offset | Description | + +----------+--------+--------+-------------------------------------------+ + | offset | 4 | 0 | offset in QEMU's NFIT structures blob to | + | | | | read from | + +----------+--------+--------+-------------------------------------------+ + + Output layout in the dsm memory page: + +----------+--------+--------+-------------------------------------------+ + | Field | Length | Offset | Description | + +----------+--------+--------+-------------------------------------------+ + | length | 4 | 0 | length of entire returned data | + | | | | (including this header) | + +----------+-----------------+-------------------------------------------+ + | | | | return status codes | + | | | | 0x0 - success | + | | | | 0x100 - error caused by NFIT update while | + | status | 4 | 4 | read by _FIT wasn't completed, other | + | | | | codes follow Chapter 3 in DSM Spec Rev1 | + +----------+-----------------+-------------------------------------------+ + | fit data | Varies | 8 | contains FIT data, this field is present | + | | | | if status field is 0; | + +----------+--------+--------+-------------------------------------------+ + + The FIT offset is maintained by the OSPM itself, current offset plus + the size of the fit data returned by the function is the next offset + OSPM should read. When all FIT data has been read out, zero fit data + size is returned. + + If it returns status code 0x100, OSPM should restart to read FIT (read + from offset 0 again). |