On Mon, 19 Jul 2021 12:01:10 +0200 Philippe Mathieu-Daudé <f4...@amsat.org> wrote:
> Hi Hiroko, > > On 7/19/21 11:34 AM, Hiroko Shimizu wrote: > > Hello, > > I'd like to initialize RAM from a specific file when RAM is created. > > Then, I tried using memory_region_init_ram_from_file(). ... > > Could you tell me what I need to do or another way to initialize RAM > > from a file? > > > > Also, is it possible to save RAM's value to the file when a value is > > written to RAM which is initialized memory_region_init_ram_from_file()? > > 2 years ago I was using -mem-path /dev/shm/ (and maybe -mem-prealloc) to > keep the ram sync on a file, pause the VM and analyse the memory, but it > stopped working after the global memdev refactor. I don't think my use -mem-path should still work as it's aliased to default memdev, (see: create_default_memdev), that's assumes legacy CLI and that board uses MachineState::ram as RAM. (it certainly worked on mainstream boards, if you share your CLI I can look if it's expected or a bug). For new CLI: it's recommended to use '-machine memory-backend=' which points to previously specified file backend, ex: -object memory-backend-file,id=myram,share=yes,size=1G,mem-path=/ram-image-file \ -machine memory-backend=myram Above will create memory region and assign it to MachineState::ram, so one should use that instead of manually calling memory_region_init_ram_from_file(). > case was the expected one. Maybe I simply need to adapt to a new command > line format :) > > Now I use 'pmemsave' from the monitor: > > pmemsave addr size file -- save to disk physical memory dump starting at > 'addr' of size 'size' > > If attached from GDB: > > (gdb) monitor pmemsave 0x20000000 0x1000000 /tmp/ram.dump > > There are other commands and probably a clever way to do that. > > See also the VM snapshot feature, described here, which might be > what you are looking for: > https://translatedcode.wordpress.com/2015/07/06/tricks-for-debugging-qemu-savevm-snapshots/ > > Regards, > > Phil. >
