> -----Original Message----- > From: Tan, Jianfeng > Sent: Saturday, February 24, 2018 11:08 AM > To: 'Igor Mammedov' > Cc: Paolo Bonzini; Jason Wang; Maxime Coquelin; qemu-devel@nongnu.org; > Michael S . Tsirkin > Subject: RE: [Qemu-devel] [RFC] exec: eliminate ram naming issue as > migration > > Hi Igor and all, > > > -----Original Message----- > > From: Igor Mammedov [mailto:imamm...@redhat.com] > > Sent: Thursday, February 8, 2018 7:30 PM > > To: Tan, Jianfeng > > Cc: Paolo Bonzini; Jason Wang; Maxime Coquelin; qemu- > de...@nongnu.org; > > Michael S . Tsirkin > > Subject: Re: [Qemu-devel] [RFC] exec: eliminate ram naming issue as > > migration > > > [...] > > > > It could be solved by adding memdev option to machine, > > > > which would allow to specify backend object. And then on > > > > top make -mem-path alias new option to clean thing up. > > > > > > Do you mean? > > > > > > src vm: -m xG > > > dst vm: -m xG,memdev=pc.ram -object memory-backend- > file,id=pc.ram,size=xG,mem-path=xxx,share=on ... > > Yep, I've meant something like it > > > > src vm: -m xG,memdev=SHARED_RAM -object memory-backend- > file,id=SHARED_RAM,size=xG,mem-path=xxx,share=on > > dst vm: -m xG,memdev=SHARED_RAM -object memory-backend- > file,id=SHARED_RAM,size=xG,mem-path=xxx,share=on > > After a second thought, I find adding a backend for nonnuma pc RAM is > roundabout way. > > And we actually have an existing way to add a file-backed RAM: commit > c902760fb25f ("Add option to use file backed guest memory"). Basically, this > commit adds two options, --mem-path and --mem-prealloc, without specify > a backend explicitly. > > So how about just adding a new option --mem-share to decide if that's a > private memory or shared memory? That seems much straightforward way > to me; after this change we can migrate like: > > src vm: -m xG > dst vm: -m xG --mem-path xxx --mem-share >
Attach the patch FYI. Look forward to your thoughts. diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h index 31612ca..5eaf367 100644 --- a/include/sysemu/sysemu.h +++ b/include/sysemu/sysemu.h @@ -127,6 +127,7 @@ extern bool enable_mlock; extern uint8_t qemu_extra_params_fw[2]; extern QEMUClockType rtc_clock; extern const char *mem_path; +extern int mem_share; extern int mem_prealloc; #define MAX_NODES 128 diff --git a/numa.c b/numa.c index 7b9c33a..322289f 100644 --- a/numa.c +++ b/numa.c @@ -456,7 +456,7 @@ static void allocate_system_memory_nonnuma(MemoryRegion *mr, Object *owner, if (mem_path) { #ifdef __linux__ Error *err = NULL; - memory_region_init_ram_from_file(mr, owner, name, ram_size, false, + memory_region_init_ram_from_file(mr, owner, name, ram_size, mem_share, mem_path, &err); if (err) { error_report_err(err); diff --git a/qemu-options.hx b/qemu-options.hx index 678181c..c968c53 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -389,6 +389,15 @@ STEXI Allocate guest RAM from a temporarily created file in @var{path}. ETEXI +DEF("mem-share", 0, QEMU_OPTION_memshare, + "-mem-share make guest memory shareable (use with -mem-path)\n", + QEMU_ARCH_ALL) +STEXI +@item -mem-share +@findex -mem-share +Make file-backed guest RAM shareable when using -mem-path. +ETEXI + DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc, "-mem-prealloc preallocate guest memory (use with -mem-path)\n", QEMU_ARCH_ALL) diff --git a/vl.c b/vl.c index 444b750..0ff06c2 100644 --- a/vl.c +++ b/vl.c @@ -140,6 +140,7 @@ int display_opengl; const char* keyboard_layout = NULL; ram_addr_t ram_size; const char *mem_path = NULL; +int mem_share = 0; int mem_prealloc = 0; /* force preallocation of physical target memory */ bool enable_mlock = false; int nb_nics; @@ -3395,6 +3396,9 @@ int main(int argc, char **argv, char **envp) case QEMU_OPTION_mempath: mem_path = optarg; break; + case QEMU_OPTION_memshare: + mem_share = 1; + break; case QEMU_OPTION_mem_prealloc: mem_prealloc = 1; break;