From 0631aaae31cccf5ae61e8c67c198e064bfaafc66 Mon Sep 17 00:00:00 2001 From: Anup Patel Date: Sun, 20 Feb 2022 14:25:26 +0530 Subject: [PATCH] hw/riscv: virt: Increase maximum number of allowed CPUs To facilitate software development of RISC-V systems with large number of HARTs, we increase the maximum number of allowed CPUs to 512 (2^9). We also add a detailed source level comments about limit defines which impact the physical address space utilization. Signed-off-by: Anup Patel Signed-off-by: Anup Patel Reviewed-by: Alistair Francis Reviewed-by: Frank Chang Message-Id: <20220220085526.808674-6-anup@brainfault.org> Signed-off-by: Alistair Francis --- hw/riscv/virt.c | 10 ++++++++++ include/hw/riscv/virt.h | 2 +- 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c index 94fbf63ec8..da50cbed43 100644 --- a/hw/riscv/virt.c +++ b/hw/riscv/virt.c @@ -45,6 +45,16 @@ #include "hw/pci-host/gpex.h" #include "hw/display/ramfb.h" +/* + * The virt machine physical address space used by some of the devices + * namely ACLINT, PLIC, APLIC, and IMSIC depend on number of Sockets, + * number of CPUs, and number of IMSIC guest files. + * + * Various limits defined by VIRT_SOCKETS_MAX_BITS, VIRT_CPUS_MAX_BITS, + * and VIRT_IRQCHIP_MAX_GUESTS_BITS are tuned for maximum utilization + * of virt machine physical address space. + */ + #define VIRT_IMSIC_GROUP_MAX_SIZE (1U << IMSIC_MMIO_GROUP_MIN_SHIFT) #if VIRT_IMSIC_GROUP_MAX_SIZE < \ IMSIC_GROUP_SIZE(VIRT_CPUS_MAX_BITS, VIRT_IRQCHIP_MAX_GUESTS_BITS) diff --git a/include/hw/riscv/virt.h b/include/hw/riscv/virt.h index d248d0dfa0..78b058ec86 100644 --- a/include/hw/riscv/virt.h +++ b/include/hw/riscv/virt.h @@ -24,7 +24,7 @@ #include "hw/block/flash.h" #include "qom/object.h" -#define VIRT_CPUS_MAX_BITS 3 +#define VIRT_CPUS_MAX_BITS 9 #define VIRT_CPUS_MAX (1 << VIRT_CPUS_MAX_BITS) #define VIRT_SOCKETS_MAX_BITS 2 #define VIRT_SOCKETS_MAX (1 << VIRT_SOCKETS_MAX_BITS)