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authorAnup Patel <anup.patel@wdc.com>2022-02-20 14:25:26 +0530
committerAlistair Francis <alistair.francis@wdc.com>2022-03-03 13:14:50 +1000
commit0631aaae31cccf5ae61e8c67c198e064bfaafc66 (patch)
treeec2a60aac36861b8aa015c4e68bfdeb7803e4f3d /hw/riscv
parentc65bc383edc7aa7c12afcdad3be30521b3280203 (diff)
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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 <anup.patel@wdc.com> Signed-off-by: Anup Patel <anup@brainfault.org> Reviewed-by: Alistair Francis <alistair.francis@wdc.com> Reviewed-by: Frank Chang <frank.chang@sifive.com> Message-Id: <20220220085526.808674-6-anup@brainfault.org> Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Diffstat (limited to 'hw/riscv')
-rw-r--r--hw/riscv/virt.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
index 94fbf63..da50cbe 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)