target/riscv: Add short-isa-string option

Because some operating systems don't correctly parse long ISA extension
string, this commit adds short-isa-string boolean option to disable
generating long ISA extension strings on Device Tree.

For instance, enabling Zfinx and Zdinx extensions and booting Linux (5.17 or
earlier) with FPU support caused a kernel panic.

Operating Systems which short-isa-string might be helpful:

1.  Linux (5.17 or earlier)
2.  FreeBSD (at least 14.0-CURRENT)
3.  OpenBSD (at least current development version)

Signed-off-by: Tsukasa OI <research_trasio@irq.a4lg.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <7c1fe5f06b0a7646a47e9bcdddb1042bb60c69c8.1652181972.git.research_trasio@irq.a4lg.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index fe6c9a2..f5ff729 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -425,6 +425,8 @@ struct RISCVCPUConfig {
     bool aia;
     bool debug;
     uint64_t resetvec;
+
+    bool short_isa_string;
 };
 
 typedef struct RISCVCPUConfig RISCVCPUConfig;