Re: [SeaBIOS] [RFC PATCH v2 03/21] acpi-dsdt: Implement functions for memory hotplug

[Wen Congyang]

At 07/11/2012 06:31 PM, Vasilis Liaskovitis Wrote:
> Extend the DSDT to include methods for handling memory hot-add and hot-remove
> notifications and memory device status requests. These functions are called
> from the memory device SSDT methods.
> Signed-off-by: Vasilis Liaskovitis
>
> src/acpi-dsdt.dsl |   70 +++++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 files changed, 68 insertions(+), 2 deletions(-)
>
> diff --git a/src/acpi-dsdt.dsl b/src/acpi-dsdt.dsl
> index 2060686..5d3e92b 100644
> --- a/src/acpi-dsdt.dsl
> +++ b/src/acpi-dsdt.dsl
> @@ -737,6 +737,71 @@ DefinitionBlock (
>              }
>              Return(One)
>          }
>    /* Objects filled in by run-time generated SSDT */
>    External(MTFY, MethodObj)
>    External(MEON, PkgObj)
>    Method (CMST, 1, NotSerialized) {
>        // _STA method - return ON status of memdevice
>        // Local0 = MEON flag for this cpu
>        Store(DerefOf(Index(MEON, Arg0)), Local0)
>        If (Local0) { Return(0xF) } Else { Return(0x0) }
>    }
>    /* Memory hotplug notify array */
>    OperationRegion(MEST, SystemIO, 0xaf80, 32)
>    Field (MEST, ByteAcc, NoLock, Preserve)
>    {
>        MES, 256
>    }
>    /* Memory eject byte */
>    OperationRegion(MEMJ, SystemIO, 0xafa0, 1)
>    Field (MEMJ, ByteAcc, NoLock, Preserve)
>    {
>        MPE, 8
>    }
>    Method(MESC, 0) {
>        // Local5 = active memdevice bitmap
>        Store (MES, Local5)
>        // Local2 = last read byte from bitmap
>        Store (Zero, Local2)
>        // Local0 = memory device iterator
>        Store (Zero, Local0)
>        While (LLess(Local0, SizeOf(MEON))) {
>            // Local1 = MEON flag for this memory device
>            Store(DerefOf(Index(MEON, Local0)), Local1)
>            If (And(Local0, 0x07)) {
>                // Shift down previously read bitmap byte
>                ShiftRight(Local2, 1, Local2)
>            } Else {
>                // Read next byte from memdevice bitmap
>                Store(DerefOf(Index(Local5, ShiftRight(Local0, 3))), Local2)
>            }
>            // Local3 = active state for this memory device
>            Store(And(Local2, 1), Local3)
>            If (LNotEqual(Local1, Local3)) {

There are two ways to hot remove a memory device:
1. dimm_del
2. echo 1 >/sys/bus/acpi/devices/PNP0C80:XX/eject

In the 2nd case, we cannot hotplug this memory device again,
because both Local1 and Local3 are 1.

So, I think MEON flag for this meory device should be set to 0 in method _EJ0
or implement method _PS3 for memory device.

Thanks
Wen Congyang
>                // State change - update MEON with new state
>                Store(Local3, Index(MEON, Local0))
>                // Do MEM notify
>                If (LEqual(Local3, 1)) {
>                    MTFY(Local0, 1)
>                } Else {
>                    MTFY(Local0, 3)
>                }
>            }
>            Increment(Local0)
>        }
>        Return(One)
>    }
>    Method (MPEJ, 2, NotSerialized) {
>        // _EJ0 method - eject callback
>        Store(Arg0, MPE)
>        Sleep(200)
>    }
> }
>
> @@ -759,8 +824,9 @@ DefinitionBlock (
>              // CPU hotplug event
>              Return(_SB.PRSC())
>          }
>    Method(_L03) {
>        Return(0x01)
>    Method(_E03) {
>        // Memory hotplug event
>        Return(\_SB.MESC())
>    }
>    Method(_L04) {
>        Return(0x01)

[RFC PATCH v2 03/21] acpi-dsdt: Implement functions for memory hotplug

[Vasilis Liaskovitis]

On Tue, Jul 17, 2012 at 03:23:00PM +0800, Wen Congyang wrote:
> >    Method(MESC, 0) {
> >        // Local5 = active memdevice bitmap
> >        Store (MES, Local5)
> >        // Local2 = last read byte from bitmap
> >        Store (Zero, Local2)
> >        // Local0 = memory device iterator
> >        Store (Zero, Local0)
> >        While (LLess(Local0, SizeOf(MEON))) {
> >            // Local1 = MEON flag for this memory device
> >            Store(DerefOf(Index(MEON, Local0)), Local1)
> >            If (And(Local0, 0x07)) {
> >                // Shift down previously read bitmap byte
> >                ShiftRight(Local2, 1, Local2)
> >            } Else {
> >                // Read next byte from memdevice bitmap
> >                Store(DerefOf(Index(Local5, ShiftRight(Local0, 3))), Local2)
> >            }
> >            // Local3 = active state for this memory device
> >            Store(And(Local2, 1), Local3)
> >            If (LNotEqual(Local1, Local3)) {
>
> There are two ways to hot remove a memory device:
> dimm_del
> echo 1 >/sys/bus/acpi/devices/PNP0C80:XX/eject
>
> In the 2nd case, we cannot hotplug this memory device again,
> because both Local1 and Local3 are 1.
>
> So, I think MEON flag for this meory device should be set to 0 in method _EJ0
> or implement method _PS3 for memory device.

good catch. Both internal seabios state (MEON) and the machine qemu bitmap
(mems_sts in hw/acpi_piix4.c) have to be updated when the ejection comes from
OSPM action. I will implement a _PS3 method that updates the MEON flag and also
signals qemu to change the mems_sts bitmap.

thanks,
- Vasilis