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[Qemu-devel] [PATCH v2] RISC-V: Ignore the S and U letters when formatti
From: |
Palmer Dabbelt |
Subject: |
[Qemu-devel] [PATCH v2] RISC-V: Ignore the S and U letters when formatting ISA strings |
Date: |
Tue, 13 Aug 2019 15:53:07 -0700 |
The ISA strings we're providing from QEMU aren't actually legal RISC-V
ISA strings, as both S and U cannot exist as single-letter extensions
and must instead be multi-letter strings. We're still using the ISA
strings inside QEMU to track the availiable extensions, so this patch
just strips out the S and U extensions when formatting ISA strings.
This boots Linux on top of 4.1-rc3, which no longer has the U extension
in /proc/cpuinfo.
Signed-off-by: Palmer Dabbelt <address@hidden>
---
target/riscv/cpu.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index f8d07bd20ad7..a67c54c738ba 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -501,7 +501,23 @@ char *riscv_isa_string(RISCVCPU *cpu)
char *p = isa_str + snprintf(isa_str, maxlen, "rv%d", TARGET_LONG_BITS);
for (i = 0; i < sizeof(riscv_exts); i++) {
if (cpu->env.misa & RV(riscv_exts[i])) {
- *p++ = qemu_tolower(riscv_exts[i]);
+ char lower = qemu_tolower(riscv_exts[i]);
+ switch (lower) {
+ case 's':
+ case 'u':
+ /*
+ * The 's' and 'u' letters shouldn't show up in ISA strings as
+ * they're not extensions, but they should show up in MISA.
+ * Since we use these letters interally as a pseudo ISA string
+ * to set MISA it's easier to just strip them out when
+ * formatting the ISA string.
+ */
+ break;
+
+ default:
+ *p++ = lower;
+ break;
+ }
}
}
*p = '\0';
--
2.21.0
- [Qemu-devel] [PATCH v2] RISC-V: Ignore the S and U letters when formatting ISA strings,
Palmer Dabbelt <=