[Qemu-devel] [PATCH v4 6/8] target/mips: Define the R5900 CPU

[Fredrik Noring]

The primary purpose of this change is to support programs compiled by
GCC for the R5900 target and thereby run R5900 Linux distributions, for
example Gentoo. In particular, this avoids issues with cross compilation.

This change has been tested with Gentoo compiled for R5900, including
native compilation of several packages under QEMU.

Signed-off-by: Fredrik Noring <address@hidden>
---
 target/mips/translate_init.inc.c | 47 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/target/mips/translate_init.inc.c b/target/mips/translate_init.inc.c
index b3320b9dc7..71fd83de06 100644
--- a/target/mips/translate_init.inc.c
+++ b/target/mips/translate_init.inc.c
@@ -410,6 +410,53 @@ const mips_def_t mips_defs[] =
         .insn_flags = CPU_MIPS32R5 | ASE_MSA,
         .mmu_type = MMU_TYPE_R4000,
     },
+    {
+        .name = "R5900",
+        .CP0_PRid = 0x00003800,
+        /* No L2 cache, icache size 32k, dcache size 32k, uncached coherency. 
*/
+        .CP0_Config0 = (0x3 << 9) | (0x3 << 6) | (0x2 << CP0C0_K0),
+        .CP0_Status_rw_bitmask = 0xF4C79C1F,
+#ifdef CONFIG_USER_ONLY
+        /*
+         * R5900 hardware traps to the Linux kernel for IEEE 754-1985 and LL/SC
+         * emulation. For user only, QEMU is the kernel, so we emulate the 
traps
+         * by simply emulating the instructions directly.
+         *
+         * Note: Config1 is only used internally, the R5900 has only Config0.
+         */
+        .CP0_Config1 = (1 << CP0C1_FP) | (47 << CP0C1_MMU),
+        .CP0_LLAddr_rw_bitmask = 0xFFFFFFFF,
+        .CP0_LLAddr_shift = 4,
+        .CP1_fcr0 = (0x38 << FCR0_PRID) | (0x0 << FCR0_REV),
+        .CP1_fcr31 = 0,
+        .CP1_fcr31_rw_bitmask = 0x0183FFFF,
+#else
+        /*
+         * The R5900 COP1 FPU implements single-precision floating-point
+         * operations but is not entirely IEEE 754-1985 compatible. In
+         * particular,
+         *
+         * - NaN (not a number) and plus/minus infinities are not supported;
+         * - exception mechanisms are not fully supported;
+         * - denormalized numbers are not supported;
+         * - rounding towards nearest and plus/minus infinities are not 
supported;
+         * - computed results usually differs in the least significant bit;
+         * - saturating instructions can differ more than the least 
significant bit.
+         *
+         * Since only rounding towards zero is supported, the two least
+         * significant bits of FCR31 are hardwired to 01.
+         *
+         * FPU emulation is disabled here until it is implemented.
+         *
+         * Note: Config1 is only used internally, the R5900 has only Config0.
+         */
+        .CP0_Config1 = (47 << CP0C1_MMU),
+#endif /* !CONFIG_USER_ONLY */
+        .SEGBITS = 32,
+        .PABITS = 32,
+        .insn_flags = CPU_R5900,
+        .mmu_type = MMU_TYPE_R4000,
+    },
     {
         /* A generic CPU supporting MIPS32 Release 6 ISA.
            FIXME: Support IEEE 754-2008 FP.
-- 
2.16.4