Re: CXL volatile memory is not listed
On Fri, 18 Aug 2023 10:48:35 +0530 Maverickk 78 wrote: > Hi Jonathan, > > The use case of CXL switch will always need some sort of management > agent + FM configuring the available CXL memory connected. > > In most cases it would be bmc controller configuring MLD/MHD's to > host, and in very rare scenarios it may be one of the host interacting > with FM firmware inside the switch which would do the trick. > > Another use case is static hardcoding between CXL memory & host in > built in cxl switch > > There is no scenario where one of the host BIOS can push the select > CXL memory to itself. > > > Is my understanding correct? It's possible that a particular set of systems work on the basis of the FM (BMC) in a memory appliance etc having already set up the memory before the hosts using it are booted. This would be done for legacy systems / unaware operating systems for instances. In those cases the BIOS could enumerate and configure everything present when it starts and provide that info the the OS running on the host as EFI (and/or e820) and SRAT etc. If doing more dynamic memory pooling, I'd expect the OS to do all the hard work. Note a common case in real systems is likely to be Multi Head devices for memory pooling, but they also require configuration before the memory is available to the host, so the points above are the same. Jonathan > > > > On Fri, 11 Aug 2023 at 19:25, Jonathan Cameron > wrote: > > > > On Fri, 11 Aug 2023 08:04:26 +0530 > > Maverickk 78 wrote: > > > > > Jonathan, > > > > > > > More generally for the flow that would bring the memory up as system ram > > > > you would typically need the bios to have done the CXL enumeration or > > > > a bunch of scripts in the kernel to have done it. In general it can't > > > > be fully automated, because there are policy decisions to make on > > > > things like > > > > interleaving. > > > > > > BIOS CXL enumeration? is CEDT not enough? or BIOS further needs to > > > create an entry > > > in the e820 table? > > On intel platforms 'maybe' :) I know how it works on those that just > > use the nice standard EFI tables - less familiar with the e820 stuff :) > > > > CEDT says where to find the the various bits of system related CXL stuff. > > Nothing in there on the configuration that should be used such as > > interleaving > > as that depends on what the administrator wants. Or on what the BIOS has > > decided the users should have. > > > > > > > > > > > > > I'm not aware of any open source BIOSs that do it yet. So you have > > > > to rely on the same kernel paths as for persistent memory - manual > > > > configuration > > > > etc in the kernel. > > > > > > > Manual works with "cxl create regiton" :) > > Great. > > > > Jonathan > > > > > > > > On Thu, 10 Aug 2023 at 16:05, Jonathan Cameron > > > wrote: > > > > > > > > On Wed, 9 Aug 2023 04:21:47 +0530 > > > > Maverickk 78 wrote: > > > > > > > > > Hello, > > > > > > > > > > I am running qemu-system-x86_64 > > > > > > > > > > qemu-system-x86_64 --version > > > > > QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) > > > > > > > > > +Cc linux-cxl as the answer is more todo with linux than qemu. > > > > > > > > > qemu-system-x86_64 \ > > > > > -m 2G,slots=4,maxmem=4G \ > > > > > -smp 4 \ > > > > > -machine type=q35,accel=kvm,cxl=on \ > > > > > -enable-kvm \ > > > > > -nographic \ > > > > > -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ > > > > > -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ > > > > > -object > > > > > memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ > > > > > -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ > > > > > -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G > > > > > > > > There are some problems upstream at the moment (probably not cxl > > > > related but > > > > I'm digging). So today I can't boot an x86 machine. (goody) > > > > > > > > > > > > More generally for the flow that would bring the memory up as system ram > > > > you would typically need the bios to have done the CXL enumeration or > > > > a bunch of scripts in the kernel to have done it. In general it can't > > > > be fully automated, because there are policy decisions to make on > > > > things like > > > > interleaving. > > > > > > > > I'm not aware of any open source BIOSs that do it yet. So you have > > > > to rely on the same kernel paths as for persistent memory - manual > > > > configuration > > > > etc in the kernel. > > > > > > > > There is support in ndctl for those enabling flows, so I'd look there > > > > for more information > > > > > > > > Jonathan > > > > > > > > > > > > > > > > > > > > > > > I was expecting the CXL memory to be listed in "System Ram", the lsmem > > > > > shows only 2G memory which is System RAM, it's not listing the CXL > > > > > memory. > > > > > > > > > > Do I need to pass any particular parameter in the kernel command line? > > > > > > > > > > Is there any documentation
Re: CXL volatile memory is not listed
On Fri, 18 Aug 2023 11:30:55 + Shreyas Shah wrote: > Once the cxl memory is online, how does Operating system know whether to > malloc in the cxl memory or socket attached DDR memory? If you've brought the memory up as 'normal memory' via kmem rather than the other dax options then it'll be a separate NUMA node. Hence you can control allocations using same tools used on multiple numa node systems. Jonathan > > > > [https://static1.squarespace.com/static/60dbbd6d597c966b91a3b27b/t/6104415e6177af1589fb05e4/1627668830393/elastics-cloud-logo-120.png]<https://www.elastics.cloud/> > Shreyas Shah > Founder, CTO and Chief Scientist, Elastics.cloud, Inc. > 1730 North First Street, 5th Floor, San Jose, CA 95112 > t: 408 476 3100 | e: email: shreyas.shah@elastics.cloud > > > From: Maverickk 78 > Sent: Thursday, August 17, 2023 10:18 PM > To: Jonathan Cameron > Cc: Jonathan Cameron via ; linux-...@vger.kernel.org > > Subject: Re: CXL volatile memory is not listed > > Hi Jonathan, > > The use case of CXL switch will always need some sort of management > agent + FM configuring the available CXL memory connected. > > In most cases it would be bmc controller configuring MLD/MHD's to > host, and in very rare scenarios it may be one of the host interacting > with FM firmware inside the switch which would do the trick. > > Another use case is static hardcoding between CXL memory & host in > built in cxl switch > > There is no scenario where one of the host BIOS can push the select > CXL memory to itself. > > > Is my understanding correct? > > > > On Fri, 11 Aug 2023 at 19:25, Jonathan Cameron > wrote: > > > > On Fri, 11 Aug 2023 08:04:26 +0530 > > Maverickk 78 wrote: > > > > > Jonathan, > > > > > > > More generally for the flow that would bring the memory up as system ram > > > > you would typically need the bios to have done the CXL enumeration or > > > > a bunch of scripts in the kernel to have done it. In general it can't > > > > be fully automated, because there are policy decisions to make on > > > > things like > > > > interleaving. > > > > > > BIOS CXL enumeration? is CEDT not enough? or BIOS further needs to > > > create an entry > > > in the e820 table? > > On intel platforms 'maybe' :) I know how it works on those that just > > use the nice standard EFI tables - less familiar with the e820 stuff :) > > > > CEDT says where to find the the various bits of system related CXL stuff. > > Nothing in there on the configuration that should be used such as > > interleaving > > as that depends on what the administrator wants. Or on what the BIOS has > > decided the users should have. > > > > > > > > > > > > > I'm not aware of any open source BIOSs that do it yet. So you have > > > > to rely on the same kernel paths as for persistent memory - manual > > > > configuration > > > > etc in the kernel. > > > > > > > Manual works with "cxl create regiton" :) > > Great. > > > > Jonathan > > > > > > > > On Thu, 10 Aug 2023 at 16:05, Jonathan Cameron > > > wrote: > > > > > > > > On Wed, 9 Aug 2023 04:21:47 +0530 > > > > Maverickk 78 wrote: > > > > > > > > > Hello, > > > > > > > > > > I am running qemu-system-x86_64 > > > > > > > > > > qemu-system-x86_64 --version > > > > > QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) > > > > > > > > > +Cc linux-cxl as the answer is more todo with linux than qemu. > > > > > > > > > qemu-system-x86_64 \ > > > > > -m 2G,slots=4,maxmem=4G \ > > > > > -smp 4 \ > > > > > -machine type=q35,accel=kvm,cxl=on \ > > > > > -enable-kvm \ > > > > > -nographic \ > > > > > -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ > > > > > -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ > > > > > -object > > > > > memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ > > > > > -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ > > > > > -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G > > > > > > > > There are some problems upstream at the moment (probably not cxl > > > > related but > > > > I'm d
Re: CXL volatile memory is not listed
Once the cxl memory is online, how does Operating system know whether to malloc in the cxl memory or socket attached DDR memory? [https://static1.squarespace.com/static/60dbbd6d597c966b91a3b27b/t/6104415e6177af1589fb05e4/1627668830393/elastics-cloud-logo-120.png]<https://www.elastics.cloud/> Shreyas Shah Founder, CTO and Chief Scientist, Elastics.cloud, Inc. 1730 North First Street, 5th Floor, San Jose, CA 95112 t: 408 476 3100 | e: email: shreyas.shah@elastics.cloud From: Maverickk 78 Sent: Thursday, August 17, 2023 10:18 PM To: Jonathan Cameron Cc: Jonathan Cameron via ; linux-...@vger.kernel.org Subject: Re: CXL volatile memory is not listed Hi Jonathan, The use case of CXL switch will always need some sort of management agent + FM configuring the available CXL memory connected. In most cases it would be bmc controller configuring MLD/MHD's to host, and in very rare scenarios it may be one of the host interacting with FM firmware inside the switch which would do the trick. Another use case is static hardcoding between CXL memory & host in built in cxl switch There is no scenario where one of the host BIOS can push the select CXL memory to itself. Is my understanding correct? On Fri, 11 Aug 2023 at 19:25, Jonathan Cameron wrote: > > On Fri, 11 Aug 2023 08:04:26 +0530 > Maverickk 78 wrote: > > > Jonathan, > > > > > More generally for the flow that would bring the memory up as system ram > > > you would typically need the bios to have done the CXL enumeration or > > > a bunch of scripts in the kernel to have done it. In general it can't > > > be fully automated, because there are policy decisions to make on things > > > like > > > interleaving. > > > > BIOS CXL enumeration? is CEDT not enough? or BIOS further needs to > > create an entry > > in the e820 table? > On intel platforms 'maybe' :) I know how it works on those that just > use the nice standard EFI tables - less familiar with the e820 stuff :) > > CEDT says where to find the the various bits of system related CXL stuff. > Nothing in there on the configuration that should be used such as interleaving > as that depends on what the administrator wants. Or on what the BIOS has > decided the users should have. > > > > > > > > > I'm not aware of any open source BIOSs that do it yet. So you have > > > to rely on the same kernel paths as for persistent memory - manual > > > configuration > > > etc in the kernel. > > > > > Manual works with "cxl create regiton" :) > Great. > > Jonathan > > > > > On Thu, 10 Aug 2023 at 16:05, Jonathan Cameron > > wrote: > > > > > > On Wed, 9 Aug 2023 04:21:47 +0530 > > > Maverickk 78 wrote: > > > > > > > Hello, > > > > > > > > I am running qemu-system-x86_64 > > > > > > > > qemu-system-x86_64 --version > > > > QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) > > > > > > > +Cc linux-cxl as the answer is more todo with linux than qemu. > > > > > > > qemu-system-x86_64 \ > > > > -m 2G,slots=4,maxmem=4G \ > > > > -smp 4 \ > > > > -machine type=q35,accel=kvm,cxl=on \ > > > > -enable-kvm \ > > > > -nographic \ > > > > -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ > > > > -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ > > > > -object > > > > memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ > > > > -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ > > > > -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G > > > > > > There are some problems upstream at the moment (probably not cxl related > > > but > > > I'm digging). So today I can't boot an x86 machine. (goody) > > > > > > > > > More generally for the flow that would bring the memory up as system ram > > > you would typically need the bios to have done the CXL enumeration or > > > a bunch of scripts in the kernel to have done it. In general it can't > > > be fully automated, because there are policy decisions to make on things > > > like > > > interleaving. > > > > > > I'm not aware of any open source BIOSs that do it yet. So you have > > > to rely on the same kernel paths as for persistent memory - manual > > > configuration > > > etc in the kernel. > > > > > > There is support in ndctl for those enabling flows, so I'd look there > > > for more information > > > > > > Jonathan > > > > > > > > > > > > > > > > > > I was expecting the CXL memory to be listed in "System Ram", the lsmem > > > > shows only 2G memory which is System RAM, it's not listing the CXL > > > > memory. > > > > > > > > Do I need to pass any particular parameter in the kernel command line? > > > > > > > > Is there any documentation available? I followed the inputs provided in > > > > > > > > https://lore.kernel.org/linux-mm/y+csoehvlkudn...@kroah.com/T/ > > > > > > > > Is there any documentation/blog listed? > > > >
Re: CXL volatile memory is not listed
Hi Jonathan, The use case of CXL switch will always need some sort of management agent + FM configuring the available CXL memory connected. In most cases it would be bmc controller configuring MLD/MHD's to host, and in very rare scenarios it may be one of the host interacting with FM firmware inside the switch which would do the trick. Another use case is static hardcoding between CXL memory & host in built in cxl switch There is no scenario where one of the host BIOS can push the select CXL memory to itself. Is my understanding correct? On Fri, 11 Aug 2023 at 19:25, Jonathan Cameron wrote: > > On Fri, 11 Aug 2023 08:04:26 +0530 > Maverickk 78 wrote: > > > Jonathan, > > > > > More generally for the flow that would bring the memory up as system ram > > > you would typically need the bios to have done the CXL enumeration or > > > a bunch of scripts in the kernel to have done it. In general it can't > > > be fully automated, because there are policy decisions to make on things > > > like > > > interleaving. > > > > BIOS CXL enumeration? is CEDT not enough? or BIOS further needs to > > create an entry > > in the e820 table? > On intel platforms 'maybe' :) I know how it works on those that just > use the nice standard EFI tables - less familiar with the e820 stuff :) > > CEDT says where to find the the various bits of system related CXL stuff. > Nothing in there on the configuration that should be used such as interleaving > as that depends on what the administrator wants. Or on what the BIOS has > decided the users should have. > > > > > > > > > I'm not aware of any open source BIOSs that do it yet. So you have > > > to rely on the same kernel paths as for persistent memory - manual > > > configuration > > > etc in the kernel. > > > > > Manual works with "cxl create regiton" :) > Great. > > Jonathan > > > > > On Thu, 10 Aug 2023 at 16:05, Jonathan Cameron > > wrote: > > > > > > On Wed, 9 Aug 2023 04:21:47 +0530 > > > Maverickk 78 wrote: > > > > > > > Hello, > > > > > > > > I am running qemu-system-x86_64 > > > > > > > > qemu-system-x86_64 --version > > > > QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) > > > > > > > +Cc linux-cxl as the answer is more todo with linux than qemu. > > > > > > > qemu-system-x86_64 \ > > > > -m 2G,slots=4,maxmem=4G \ > > > > -smp 4 \ > > > > -machine type=q35,accel=kvm,cxl=on \ > > > > -enable-kvm \ > > > > -nographic \ > > > > -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ > > > > -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ > > > > -object > > > > memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ > > > > -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ > > > > -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G > > > > > > There are some problems upstream at the moment (probably not cxl related > > > but > > > I'm digging). So today I can't boot an x86 machine. (goody) > > > > > > > > > More generally for the flow that would bring the memory up as system ram > > > you would typically need the bios to have done the CXL enumeration or > > > a bunch of scripts in the kernel to have done it. In general it can't > > > be fully automated, because there are policy decisions to make on things > > > like > > > interleaving. > > > > > > I'm not aware of any open source BIOSs that do it yet. So you have > > > to rely on the same kernel paths as for persistent memory - manual > > > configuration > > > etc in the kernel. > > > > > > There is support in ndctl for those enabling flows, so I'd look there > > > for more information > > > > > > Jonathan > > > > > > > > > > > > > > > > > > I was expecting the CXL memory to be listed in "System Ram", the lsmem > > > > shows only 2G memory which is System RAM, it's not listing the CXL > > > > memory. > > > > > > > > Do I need to pass any particular parameter in the kernel command line? > > > > > > > > Is there any documentation available? I followed the inputs provided in > > > > > > > > https://lore.kernel.org/linux-mm/y+csoehvlkudn...@kroah.com/T/ > > > > > > > > Is there any documentation/blog listed? > > > >
Re: CXL volatile memory is not listed
Hi Fan Awesome, thanks for the info! On Fri, 11 Aug 2023 at 22:19, Fan Ni wrote: > > On Fri, Aug 11, 2023 at 07:52:25AM +0530, Maverickk 78 wrote: > > Thanks Fan, > > > > cxl create-region works like a charm :) > > > > Since this gets listed as "System Ram(kmem)", I guess the kernel > > treats it as regular memory and > > allocates it to the applications when needed? > > or is there an extra effort needed to make it available for > > applications on the host? > > > > Yes. Once it is onlined, you can use it as regular memory. > CXL memory will serve as a zero-CPU memory-only NUMA node. > You can check it with numactl -H. > > To use the cxl memory with an app, you can use > numactl --membind=numa_id app_name > #numa_id is the dedicated numa node where cxl memory sits. > > One thing to notes, kvm will not work correctly with Qemu emulation when > you try to use cxl memory for an application, so do not enable kvm. > > Fan > > > On Thu, 10 Aug 2023 at 22:03, Fan Ni wrote: > > > > > > On Wed, Aug 09, 2023 at 04:21:47AM +0530, Maverickk 78 wrote: > > > > Hello, > > > > > > > > I am running qemu-system-x86_64 > > > > > > > > qemu-system-x86_64 --version > > > > QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) > > > > > > > > qemu-system-x86_64 \ > > > > -m 2G,slots=4,maxmem=4G \ > > > > -smp 4 \ > > > > -machine type=q35,accel=kvm,cxl=on \ > > > > -enable-kvm \ > > > > -nographic \ > > > > -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ > > > > -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ > > > > -object > > > > memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ > > > > -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ > > > > -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G > > > > > > > > > > > > I was expecting the CXL memory to be listed in "System Ram", the lsmem > > > > shows only 2G memory which is System RAM, it's not listing the CXL > > > > memory. > > > > > > > > Do I need to pass any particular parameter in the kernel command line? > > > > > > > > Is there any documentation available? I followed the inputs provided in > > > > > > > > https://lore.kernel.org/linux-mm/y+csoehvlkudn...@kroah.com/T/ > > > > > > > > Is there any documentation/blog listed? > > > > > > If I remember it correctly, for volatile cxl memory, we need to create a > > > region and then it will be discovered as system memory and shows up. > > > > > > Try to create a region with "cxl create-region". > > > > > > Fan > > > >
Re: CXL volatile memory is not listed
On Fri, Aug 11, 2023 at 07:52:25AM +0530, Maverickk 78 wrote: > Thanks Fan, > > cxl create-region works like a charm :) > > Since this gets listed as "System Ram(kmem)", I guess the kernel > treats it as regular memory and > allocates it to the applications when needed? > or is there an extra effort needed to make it available for > applications on the host? > Yes. Once it is onlined, you can use it as regular memory. CXL memory will serve as a zero-CPU memory-only NUMA node. You can check it with numactl -H. To use the cxl memory with an app, you can use numactl --membind=numa_id app_name #numa_id is the dedicated numa node where cxl memory sits. One thing to notes, kvm will not work correctly with Qemu emulation when you try to use cxl memory for an application, so do not enable kvm. Fan > On Thu, 10 Aug 2023 at 22:03, Fan Ni wrote: > > > > On Wed, Aug 09, 2023 at 04:21:47AM +0530, Maverickk 78 wrote: > > > Hello, > > > > > > I am running qemu-system-x86_64 > > > > > > qemu-system-x86_64 --version > > > QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) > > > > > > qemu-system-x86_64 \ > > > -m 2G,slots=4,maxmem=4G \ > > > -smp 4 \ > > > -machine type=q35,accel=kvm,cxl=on \ > > > -enable-kvm \ > > > -nographic \ > > > -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ > > > -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ > > > -object memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true > > > \ > > > -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ > > > -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G > > > > > > > > > I was expecting the CXL memory to be listed in "System Ram", the lsmem > > > shows only 2G memory which is System RAM, it's not listing the CXL > > > memory. > > > > > > Do I need to pass any particular parameter in the kernel command line? > > > > > > Is there any documentation available? I followed the inputs provided in > > > > > > https://lore.kernel.org/linux-mm/y+csoehvlkudn...@kroah.com/T/ > > > > > > Is there any documentation/blog listed? > > > > If I remember it correctly, for volatile cxl memory, we need to create a > > region and then it will be discovered as system memory and shows up. > > > > Try to create a region with "cxl create-region". > > > > Fan > > >
Re: CXL volatile memory is not listed
On Fri, 11 Aug 2023 08:04:26 +0530 Maverickk 78 wrote: > Jonathan, > > > More generally for the flow that would bring the memory up as system ram > > you would typically need the bios to have done the CXL enumeration or > > a bunch of scripts in the kernel to have done it. In general it can't > > be fully automated, because there are policy decisions to make on things > > like > > interleaving. > > BIOS CXL enumeration? is CEDT not enough? or BIOS further needs to > create an entry > in the e820 table? On intel platforms 'maybe' :) I know how it works on those that just use the nice standard EFI tables - less familiar with the e820 stuff :) CEDT says where to find the the various bits of system related CXL stuff. Nothing in there on the configuration that should be used such as interleaving as that depends on what the administrator wants. Or on what the BIOS has decided the users should have. > > > > > I'm not aware of any open source BIOSs that do it yet. So you have > > to rely on the same kernel paths as for persistent memory - manual > > configuration > > etc in the kernel. > > > Manual works with "cxl create regiton" :) Great. Jonathan > > On Thu, 10 Aug 2023 at 16:05, Jonathan Cameron > wrote: > > > > On Wed, 9 Aug 2023 04:21:47 +0530 > > Maverickk 78 wrote: > > > > > Hello, > > > > > > I am running qemu-system-x86_64 > > > > > > qemu-system-x86_64 --version > > > QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) > > > > > +Cc linux-cxl as the answer is more todo with linux than qemu. > > > > > qemu-system-x86_64 \ > > > -m 2G,slots=4,maxmem=4G \ > > > -smp 4 \ > > > -machine type=q35,accel=kvm,cxl=on \ > > > -enable-kvm \ > > > -nographic \ > > > -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ > > > -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ > > > -object memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true > > > \ > > > -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ > > > -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G > > > > There are some problems upstream at the moment (probably not cxl related but > > I'm digging). So today I can't boot an x86 machine. (goody) > > > > > > More generally for the flow that would bring the memory up as system ram > > you would typically need the bios to have done the CXL enumeration or > > a bunch of scripts in the kernel to have done it. In general it can't > > be fully automated, because there are policy decisions to make on things > > like > > interleaving. > > > > I'm not aware of any open source BIOSs that do it yet. So you have > > to rely on the same kernel paths as for persistent memory - manual > > configuration > > etc in the kernel. > > > > There is support in ndctl for those enabling flows, so I'd look there > > for more information > > > > Jonathan > > > > > > > > > > > > > I was expecting the CXL memory to be listed in "System Ram", the lsmem > > > shows only 2G memory which is System RAM, it's not listing the CXL > > > memory. > > > > > > Do I need to pass any particular parameter in the kernel command line? > > > > > > Is there any documentation available? I followed the inputs provided in > > > > > > https://lore.kernel.org/linux-mm/y+csoehvlkudn...@kroah.com/T/ > > > > > > Is there any documentation/blog listed? > >
Re: CXL volatile memory is not listed
Thanks Phil, David and Fan Looks like it was an error from my side due to lack of information cxl create-region works :) On Thu, 10 Aug 2023 at 16:29, Philippe Mathieu-Daudé wrote: > > Hi, > > Cc'ing Igor and David. > > On 9/8/23 00:51, Maverickk 78 wrote: > > Hello, > > > > I am running qemu-system-x86_64 > > > > qemu-system-x86_64 --version > > QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) > > > > qemu-system-x86_64 \ > > -m 2G,slots=4,maxmem=4G \ > > -smp 4 \ > > -machine type=q35,accel=kvm,cxl=on \ > > -enable-kvm \ > > -nographic \ > > -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ > > -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ > > -object memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ > > -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ > > -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G > > > > > > I was expecting the CXL memory to be listed in "System Ram", the lsmem > > shows only 2G memory which is System RAM, it's not listing the CXL > > memory. > > Sounds like a bug. Do you mind reporting at > https://gitlab.com/qemu-project/qemu/-/issues? > > Thanks, > > Phil. > > > Do I need to pass any particular parameter in the kernel command line? > > > > Is there any documentation available? I followed the inputs provided in > > > > https://lore.kernel.org/linux-mm/y+csoehvlkudn...@kroah.com/T/ > > > > Is there any documentation/blog listed? > > >
Re: CXL volatile memory is not listed
Jonathan, > More generally for the flow that would bring the memory up as system ram > you would typically need the bios to have done the CXL enumeration or > a bunch of scripts in the kernel to have done it. In general it can't > be fully automated, because there are policy decisions to make on things like > interleaving. BIOS CXL enumeration? is CEDT not enough? or BIOS further needs to create an entry in the e820 table? > > I'm not aware of any open source BIOSs that do it yet. So you have > to rely on the same kernel paths as for persistent memory - manual > configuration > etc in the kernel. > Manual works with "cxl create regiton" :) On Thu, 10 Aug 2023 at 16:05, Jonathan Cameron wrote: > > On Wed, 9 Aug 2023 04:21:47 +0530 > Maverickk 78 wrote: > > > Hello, > > > > I am running qemu-system-x86_64 > > > > qemu-system-x86_64 --version > > QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) > > > +Cc linux-cxl as the answer is more todo with linux than qemu. > > > qemu-system-x86_64 \ > > -m 2G,slots=4,maxmem=4G \ > > -smp 4 \ > > -machine type=q35,accel=kvm,cxl=on \ > > -enable-kvm \ > > -nographic \ > > -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ > > -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ > > -object memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ > > -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ > > -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G > > There are some problems upstream at the moment (probably not cxl related but > I'm digging). So today I can't boot an x86 machine. (goody) > > > More generally for the flow that would bring the memory up as system ram > you would typically need the bios to have done the CXL enumeration or > a bunch of scripts in the kernel to have done it. In general it can't > be fully automated, because there are policy decisions to make on things like > interleaving. > > I'm not aware of any open source BIOSs that do it yet. So you have > to rely on the same kernel paths as for persistent memory - manual > configuration > etc in the kernel. > > There is support in ndctl for those enabling flows, so I'd look there > for more information > > Jonathan > > > > > > > > I was expecting the CXL memory to be listed in "System Ram", the lsmem > > shows only 2G memory which is System RAM, it's not listing the CXL > > memory. > > > > Do I need to pass any particular parameter in the kernel command line? > > > > Is there any documentation available? I followed the inputs provided in > > > > https://lore.kernel.org/linux-mm/y+csoehvlkudn...@kroah.com/T/ > > > > Is there any documentation/blog listed? >
Re: CXL volatile memory is not listed
Thanks Fan, cxl create-region works like a charm :) Since this gets listed as "System Ram(kmem)", I guess the kernel treats it as regular memory and allocates it to the applications when needed? or is there an extra effort needed to make it available for applications on the host? On Thu, 10 Aug 2023 at 22:03, Fan Ni wrote: > > On Wed, Aug 09, 2023 at 04:21:47AM +0530, Maverickk 78 wrote: > > Hello, > > > > I am running qemu-system-x86_64 > > > > qemu-system-x86_64 --version > > QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) > > > > qemu-system-x86_64 \ > > -m 2G,slots=4,maxmem=4G \ > > -smp 4 \ > > -machine type=q35,accel=kvm,cxl=on \ > > -enable-kvm \ > > -nographic \ > > -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ > > -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ > > -object memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ > > -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ > > -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G > > > > > > I was expecting the CXL memory to be listed in "System Ram", the lsmem > > shows only 2G memory which is System RAM, it's not listing the CXL > > memory. > > > > Do I need to pass any particular parameter in the kernel command line? > > > > Is there any documentation available? I followed the inputs provided in > > > > https://lore.kernel.org/linux-mm/y+csoehvlkudn...@kroah.com/T/ > > > > Is there any documentation/blog listed? > > If I remember it correctly, for volatile cxl memory, we need to create a > region and then it will be discovered as system memory and shows up. > > Try to create a region with "cxl create-region". > > Fan > >
Re: CXL volatile memory is not listed
On Wed, Aug 09, 2023 at 04:21:47AM +0530, Maverickk 78 wrote: > Hello, > > I am running qemu-system-x86_64 > > qemu-system-x86_64 --version > QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) > > qemu-system-x86_64 \ > -m 2G,slots=4,maxmem=4G \ > -smp 4 \ > -machine type=q35,accel=kvm,cxl=on \ > -enable-kvm \ > -nographic \ > -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ > -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ > -object memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ > -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ > -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G > > > I was expecting the CXL memory to be listed in "System Ram", the lsmem > shows only 2G memory which is System RAM, it's not listing the CXL > memory. > > Do I need to pass any particular parameter in the kernel command line? > > Is there any documentation available? I followed the inputs provided in > > https://lore.kernel.org/linux-mm/y+csoehvlkudn...@kroah.com/T/ > > Is there any documentation/blog listed? If I remember it correctly, for volatile cxl memory, we need to create a region and then it will be discovered as system memory and shows up. Try to create a region with "cxl create-region". Fan >
Re: CXL volatile memory is not listed
On 10.08.23 12:59, Philippe Mathieu-Daudé wrote: Hi, Cc'ing Igor and David. On 9/8/23 00:51, Maverickk 78 wrote: Hello, I am running qemu-system-x86_64 qemu-system-x86_64 --version QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) qemu-system-x86_64 \ -m 2G,slots=4,maxmem=4G \ -smp 4 \ -machine type=q35,accel=kvm,cxl=on \ -enable-kvm \ -nographic \ -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ -object memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G I was expecting the CXL memory to be listed in "System Ram", the lsmem shows only 2G memory which is System RAM, it's not listing the CXL memory. We are talking about the memory via inside the guest, right? In the guest, that memory most probably has to be added as "System RAM" explicitly using the dax/kmem driver. https://lwn.net/Articles/922944/ Contains some details on how to use "daxctl reconfigure-device". -- Cheers, David / dhildenb
Re: CXL volatile memory is not listed
Hi, Cc'ing Igor and David. On 9/8/23 00:51, Maverickk 78 wrote: Hello, I am running qemu-system-x86_64 qemu-system-x86_64 --version QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) qemu-system-x86_64 \ -m 2G,slots=4,maxmem=4G \ -smp 4 \ -machine type=q35,accel=kvm,cxl=on \ -enable-kvm \ -nographic \ -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ -object memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G I was expecting the CXL memory to be listed in "System Ram", the lsmem shows only 2G memory which is System RAM, it's not listing the CXL memory. Sounds like a bug. Do you mind reporting at https://gitlab.com/qemu-project/qemu/-/issues? Thanks, Phil. Do I need to pass any particular parameter in the kernel command line? Is there any documentation available? I followed the inputs provided in https://lore.kernel.org/linux-mm/y+csoehvlkudn...@kroah.com/T/ Is there any documentation/blog listed?
Re: CXL volatile memory is not listed
On Wed, 9 Aug 2023 04:21:47 +0530 Maverickk 78 wrote: > Hello, > > I am running qemu-system-x86_64 > > qemu-system-x86_64 --version > QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) > +Cc linux-cxl as the answer is more todo with linux than qemu. > qemu-system-x86_64 \ > -m 2G,slots=4,maxmem=4G \ > -smp 4 \ > -machine type=q35,accel=kvm,cxl=on \ > -enable-kvm \ > -nographic \ > -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ > -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ > -object memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ > -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ > -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G There are some problems upstream at the moment (probably not cxl related but I'm digging). So today I can't boot an x86 machine. (goody) More generally for the flow that would bring the memory up as system ram you would typically need the bios to have done the CXL enumeration or a bunch of scripts in the kernel to have done it. In general it can't be fully automated, because there are policy decisions to make on things like interleaving. I'm not aware of any open source BIOSs that do it yet. So you have to rely on the same kernel paths as for persistent memory - manual configuration etc in the kernel. There is support in ndctl for those enabling flows, so I'd look there for more information Jonathan > > > I was expecting the CXL memory to be listed in "System Ram", the lsmem > shows only 2G memory which is System RAM, it's not listing the CXL > memory. > > Do I need to pass any particular parameter in the kernel command line? > > Is there any documentation available? I followed the inputs provided in > > https://lore.kernel.org/linux-mm/y+csoehvlkudn...@kroah.com/T/ > > Is there any documentation/blog listed?
CXL volatile memory is not listed
Hello, I am running qemu-system-x86_64 qemu-system-x86_64 --version QEMU emulator version 8.0.92 (v8.1.0-rc2-80-g0450cf0897) qemu-system-x86_64 \ -m 2G,slots=4,maxmem=4G \ -smp 4 \ -machine type=q35,accel=kvm,cxl=on \ -enable-kvm \ -nographic \ -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52 \ -device cxl-rp,id=rp0,bus=cxl.0,chassis=0,port=0,slot=0 \ -object memory-backend-file,id=mem0,mem-path=/tmp/mem0,size=1G,share=true \ -device cxl-type3,bus=rp0,volatile-memdev=mem0,id=cxl-mem0 \ -M cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.size=1G I was expecting the CXL memory to be listed in "System Ram", the lsmem shows only 2G memory which is System RAM, it's not listing the CXL memory. Do I need to pass any particular parameter in the kernel command line? Is there any documentation available? I followed the inputs provided in https://lore.kernel.org/linux-mm/y+csoehvlkudn...@kroah.com/T/ Is there any documentation/blog listed?
