diff options
Diffstat (limited to 'src/runtime/lfstack_64bit.go')
| -rw-r--r-- | src/runtime/lfstack_64bit.go | 25 |
1 files changed, 6 insertions, 19 deletions
diff --git a/src/runtime/lfstack_64bit.go b/src/runtime/lfstack_64bit.go index cf6c02895f..19d8045203 100644 --- a/src/runtime/lfstack_64bit.go +++ b/src/runtime/lfstack_64bit.go @@ -11,30 +11,17 @@ import "unsafe" const ( // addrBits is the number of bits needed to represent a virtual address. // - // In Linux the user address space for each architecture is limited as - // follows (taken from the processor.h file for the architecture): - // - // Architecture Name Maximum Value (exclusive) - // --------------------------------------------------------------------- - // amd64 TASK_SIZE_MAX 0x007ffffffff000 (47 bit addresses) - // arm64 TASK_SIZE_64 0x01000000000000 (48 bit addresses) - // ppc64{,le} TASK_SIZE_USER64 0x00400000000000 (46 bit addresses) - // mips64{,le} TASK_SIZE64 0x00010000000000 (40 bit addresses) - // s390x TASK_SIZE 1<<64 (64 bit addresses) - // - // These values may increase over time. In particular, ppc64 - // and mips64 support arbitrary 64-bit addresses in hardware, - // but Linux imposes the above limits. amd64 has hardware - // support for 57 bit addresses as of 2017 (56 bits for user - // space), but Linux only uses addresses above 1<<47 for - // mappings that explicitly pass a high hint address. + // See memLimitBits for a table of address space sizes on + // various architectures. 48 bits is enough for all + // architectures except s390x. // // On AMD64, virtual addresses are 48-bit (or 57-bit) numbers sign extended to 64. // We shift the address left 16 to eliminate the sign extended part and make // room in the bottom for the count. // - // On s390x, there's not much we can do, so we just hope that - // the kernel doesn't get to really high addresses. + // On s390x, virtual addresses are 64-bit. There's not much we + // can do about this, so we just hope that the kernel doesn't + // get to really high addresses and panic if it does. addrBits = 48 // In addition to the 16 bits taken from the top, we can take 3 from the |