Hi, all, I was able to get cma-reserved region by adding CONFIG_DMA_CMA=y. This is the result. Memory: 233708K/1048576K available (3200K kernel code, 386K rwdata, 808K rodata, 7808K init, 105K bss, 28436K reserved, 786432K cma-reserved) Thanks! Chan Kim >-----Original Message----- >From: Chan Kim <ckim@xxxxxxxxxx> >Sent: Tuesday, January 3, 2023 2:36 PM >To: kernelnewbies@xxxxxxxxxxxxxxxxx >Subject: How can I reserve contiguous mem alloc region? > >Hello kernel experts and users, > >I wanted to test cma-allocator in linux (5.15.68). >So I added linux,cma node in the /reserved-memory node like this. > > reserved-memory { > #address-cells = <2>; > #size-cells = <2>; > ranges; > > axpu_reserved_mem: axpursvd@90000000 { > no-map; > reg = <0x0 0xc0000000 0x0 0x8000000>; > }; > > linux,cma { > compatible = "shared-dma-pool"; > reusable; > size = <0 0x30000000>; > alloc-ranges = <0 0x90000000 0 0x30000000>; > linux,cma-default; > }; > }; > >BTW, this test was done on qemu arm64 machine and there is only 1GB ram >(from 0x80000000 ~ 0xbfffffff) in the virtual machine, and notice I'm >assigning 3/4 of the ram to cma region and 1/8 to a device driver (just for >test). > >When I boot the machine, I see this message during the boot. > > Memory: 1020140K/1048576K available (3200K kernel code, 386K rwdata, >808K rodata, 7808K init, 106K bss, 28436K reserved, 0K cma-reserved) > >Why is the CMA-reserved area is 0KB? >This is some config variables I added for CMA test. > > CONFIG_MEMORY_ISOLATION=y > CONFIG_CONTIG_ALLOC=y > ONFIG_CMA=y > CONFIG_CMA_DEBUG=y > CONFIG_CMA_DEBUGFS=y > CONFIG_CMA_SYSFS=y > CONFIG_CMA_AREAS=7 > # CONFIG_DMA_CMA is not set > >I tried adding 'cma=768MB' in the boot args or changed CONFIG_CMA_AREAS to 1 >but it is the same. >What am I missing?? > >Thank you. > >Chan Kim _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies