On 2024-04-17 Theodore Ts'o wrote: > On Wed, Apr 17, 2024 at 12:36:39AM +0200, Nam Cao wrote: > > > > However, I am confused about one thing: doesn't this make one page of > > physical memory inaccessible? > > So are these riscv32 systems really having multiple terabytes of > memory? Why is this page in the physical memory map in the first > place? It's 32 bit, so it doesn't take much to fill up the entire address space. Here's the memory layout from kernel boot log: [ 0.000000] Virtual kernel memory layout: [ 0.000000] fixmap : 0x9c800000 - 0x9d000000 (8192 kB) [ 0.000000] pci io : 0x9d000000 - 0x9e000000 ( 16 MB) [ 0.000000] vmemmap : 0x9e000000 - 0xa0000000 ( 32 MB) [ 0.000000] vmalloc : 0xa0000000 - 0xc0000000 ( 512 MB) [ 0.000000] lowmem : 0xc0000000 - 0x00000000 (1024 MB) Note that lowmem occupies the last 1GB, including ERR_PTR (the last address wraps to zero) Best regards, Nam
