From: Palmer Dabbelt <palmer@sifive.com>
To: qemu-riscv@nongnu.org, Alistair Francis <Alistair.Francis@wdc.com>
Cc: Atish Patra <Atish.Patra@wdc.com>,
Palmer Dabbelt <palmer@sifive.com>,
qemu-devel@nongnu.org, Paul Walmsley <paul.walmsley@sifive.com>
Subject: [Qemu-devel] [PATCH for 4.1] RISC-V: Ignore the S and U extensions when formatting ISA strings
Date: Wed, 7 Aug 2019 07:59:39 -0700 [thread overview]
Message-ID: <20190807145939.1281-1-palmer@sifive.com> (raw)
The ISA strings we're providing from QEMU aren't actually legal RISC-V
ISA strings, as both the S and U extensions 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 <palmer@sifive.com>
---
This is another late one, but I'd like to target it for 4.1 as we're
providing illegal ISA strings and I don't want to bake that into a bunch
of other code.
---
target/riscv/cpu.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index f8d07bd20ad7..4df14433d789 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -501,7 +501,22 @@ 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' extensions shouldn't be passed in the device
+ * tree, but we still use them internally to track extension
+ * sets. Here we just explicitly remove them when formatting
+ * an ISA string.
+ */
+ break;
+
+ default:
+ *p++ = qemu_tolower(riscv_exts[i]);
+ break;
+ }
}
}
*p = '\0';
--
2.21.0
next reply other threads:[~2019-08-07 15:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 14:59 Palmer Dabbelt [this message]
2019-08-07 15:27 ` [Qemu-devel] [PATCH for 4.1] RISC-V: Ignore the S and U extensions when formatting ISA strings Paul Walmsley
2019-08-07 16:08 ` Peter Maydell
2019-08-07 16:20 ` Palmer Dabbelt
2019-08-07 16:41 ` Peter Maydell
2019-08-07 17:25 ` Palmer Dabbelt
2019-08-07 17:54 ` Alistair Francis
2019-08-13 22:54 ` Palmer Dabbelt
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