| Message ID | 20221122154628.3138131-1-bmeng@tinylab.org |
|---|---|
| State | New |
| Headers | show |
| Series | target/riscv: Dump sstatus CSR in riscv_cpu_dump_state() | expand |
On Wed, Nov 23, 2022 at 2:07 AM Bin Meng <bmeng@tinylab.org> wrote: > > sstatus register dump is currently missing in riscv_cpu_dump_state(). > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1332 > Signed-off-by: Bin Meng <bmeng@tinylab.org> > > --- > > target/riscv/cpu.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c > index d14e95c9dc..80d76f0181 100644 > --- a/target/riscv/cpu.c > +++ b/target/riscv/cpu.c > @@ -382,6 +382,7 @@ static void riscv_cpu_dump_state(CPUState *cs, FILE *f, int flags) > CSR_MHARTID, > CSR_MSTATUS, > CSR_MSTATUSH, > + CSR_SSTATUS, I don't think we need this. mstatus contains all of the information already and there is limited space to print all of this information out. Alistair > CSR_HSTATUS, > CSR_VSSTATUS, > CSR_MIP, > -- > 2.34.1 > >
Hi Alistair, On Wed, Nov 23, 2022 at 8:03 AM Alistair Francis <alistair23@gmail.com> wrote: > > On Wed, Nov 23, 2022 at 2:07 AM Bin Meng <bmeng@tinylab.org> wrote: > > > > sstatus register dump is currently missing in riscv_cpu_dump_state(). > > > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1332 > > Signed-off-by: Bin Meng <bmeng@tinylab.org> > > > > --- > > > > target/riscv/cpu.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c > > index d14e95c9dc..80d76f0181 100644 > > --- a/target/riscv/cpu.c > > +++ b/target/riscv/cpu.c > > @@ -382,6 +382,7 @@ static void riscv_cpu_dump_state(CPUState *cs, FILE *f, int flags) > > CSR_MHARTID, > > CSR_MSTATUS, > > CSR_MSTATUSH, > > + CSR_SSTATUS, > > I don't think we need this. mstatus contains all of the information > already and there is limited space to print all of this information > out. > I am not sure what limited space restricts this? This is CPU state dump, and printing sstatus CSR seems reasonable to me. We do the similar thing in the gdb stub too. Regards, Bin
On Wed, Nov 23, 2022 at 2:07 PM Bin Meng <bmeng.cn@gmail.com> wrote: > > Hi Alistair, > > On Wed, Nov 23, 2022 at 8:03 AM Alistair Francis <alistair23@gmail.com> wrote: > > > > On Wed, Nov 23, 2022 at 2:07 AM Bin Meng <bmeng@tinylab.org> wrote: > > > > > > sstatus register dump is currently missing in riscv_cpu_dump_state(). > > > > > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1332 > > > Signed-off-by: Bin Meng <bmeng@tinylab.org> > > > > > > --- > > > > > > target/riscv/cpu.c | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c > > > index d14e95c9dc..80d76f0181 100644 > > > --- a/target/riscv/cpu.c > > > +++ b/target/riscv/cpu.c > > > @@ -382,6 +382,7 @@ static void riscv_cpu_dump_state(CPUState *cs, FILE *f, int flags) > > > CSR_MHARTID, > > > CSR_MSTATUS, > > > CSR_MSTATUSH, > > > + CSR_SSTATUS, > > > > I don't think we need this. mstatus contains all of the information > > already and there is limited space to print all of this information > > out. > > > > I am not sure what limited space restricts this? This is CPU state > dump, and printing sstatus CSR seems reasonable to me. We do the > similar thing in the gdb stub too. Limited space in that there is only so much text we want to dump to the screen. As new extensions are added this will continue to grow, and sstatus doesn't provide any more information then the mstatus register that we already show. GDB is a little different as people can interactively probe the registers they are interested in. Alistair > > Regards, > Bin
On Fri, Nov 25, 2022 at 7:58 AM Alistair Francis <alistair23@gmail.com> wrote: > > On Wed, Nov 23, 2022 at 2:07 PM Bin Meng <bmeng.cn@gmail.com> wrote: > > > > Hi Alistair, > > > > On Wed, Nov 23, 2022 at 8:03 AM Alistair Francis <alistair23@gmail.com> wrote: > > > > > > On Wed, Nov 23, 2022 at 2:07 AM Bin Meng <bmeng@tinylab.org> wrote: > > > > > > > > sstatus register dump is currently missing in riscv_cpu_dump_state(). > > > > > > > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1332 > > > > Signed-off-by: Bin Meng <bmeng@tinylab.org> > > > > > > > > --- > > > > > > > > target/riscv/cpu.c | 1 + > > > > 1 file changed, 1 insertion(+) > > > > > > > > diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c > > > > index d14e95c9dc..80d76f0181 100644 > > > > --- a/target/riscv/cpu.c > > > > +++ b/target/riscv/cpu.c > > > > @@ -382,6 +382,7 @@ static void riscv_cpu_dump_state(CPUState *cs, FILE *f, int flags) > > > > CSR_MHARTID, > > > > CSR_MSTATUS, > > > > CSR_MSTATUSH, > > > > + CSR_SSTATUS, > > > > > > I don't think we need this. mstatus contains all of the information > > > already and there is limited space to print all of this information > > > out. > > > > > > > I am not sure what limited space restricts this? This is CPU state > > dump, and printing sstatus CSR seems reasonable to me. We do the > > similar thing in the gdb stub too. > > Limited space in that there is only so much text we want to dump to > the screen. As new extensions are added this will continue to grow, > and sstatus doesn't provide any more information then the mstatus > register that we already show. > On a screen, yes, but we can log to a file so there is no size limitation. > GDB is a little different as people can interactively probe the > registers they are interested in. The dump routine is one of the debug methods too. If gdb stub provides $sstatus directly I think we should do the same for dump_state for consistency. Otherwise we can just provide $mstatus in gdb stub and let user figure out sstatus value. Regards, Bin
On Fri, Nov 25, 2022 at 1:34 PM Bin Meng <bmeng.cn@gmail.com> wrote: > > On Fri, Nov 25, 2022 at 7:58 AM Alistair Francis <alistair23@gmail.com> wrote: > > > > On Wed, Nov 23, 2022 at 2:07 PM Bin Meng <bmeng.cn@gmail.com> wrote: > > > > > > Hi Alistair, > > > > > > On Wed, Nov 23, 2022 at 8:03 AM Alistair Francis <alistair23@gmail.com> wrote: > > > > > > > > On Wed, Nov 23, 2022 at 2:07 AM Bin Meng <bmeng@tinylab.org> wrote: > > > > > > > > > > sstatus register dump is currently missing in riscv_cpu_dump_state(). > > > > > > > > > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1332 > > > > > Signed-off-by: Bin Meng <bmeng@tinylab.org> > > > > > > > > > > --- > > > > > > > > > > target/riscv/cpu.c | 1 + > > > > > 1 file changed, 1 insertion(+) > > > > > > > > > > diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c > > > > > index d14e95c9dc..80d76f0181 100644 > > > > > --- a/target/riscv/cpu.c > > > > > +++ b/target/riscv/cpu.c > > > > > @@ -382,6 +382,7 @@ static void riscv_cpu_dump_state(CPUState *cs, FILE *f, int flags) > > > > > CSR_MHARTID, > > > > > CSR_MSTATUS, > > > > > CSR_MSTATUSH, > > > > > + CSR_SSTATUS, > > > > > > > > I don't think we need this. mstatus contains all of the information > > > > already and there is limited space to print all of this information > > > > out. > > > > > > > > > > I am not sure what limited space restricts this? This is CPU state > > > dump, and printing sstatus CSR seems reasonable to me. We do the > > > similar thing in the gdb stub too. > > > > Limited space in that there is only so much text we want to dump to > > the screen. As new extensions are added this will continue to grow, > > and sstatus doesn't provide any more information then the mstatus > > register that we already show. > > > > On a screen, yes, but we can log to a file so there is no size limitation. And this function is commonly used as part of the HMP `info registers` command. Which is dumped to the screen. > > > GDB is a little different as people can interactively probe the > > registers they are interested in. > > The dump routine is one of the debug methods too. If gdb stub provides > $sstatus directly I think we should do the same for dump_state for > consistency. Otherwise we can just provide $mstatus in gdb stub and > let user figure out sstatus value. I feel like GDB and text register dumping are different debugging tools. When using GDB a user should be able to probe all of the registers. They can read/write to the CSRs and write scripts to interact with them if they want. When dumping the CPU state as text, we can't dump all CSRs. There are too many, it becomes unmanageable. So we have to select a small number that are the most important and most useful. As sstatus is a copy of mstatus, which is described in the priv spec, it seems redundant to print the same information twice. I feel this list is only going to become longer and longer as we enable other extensions, so we should try to avoid populating it with redundant information. It is always clear what bits are propagated to sstatus, as it's described in the spec. Alistair > > Regards, > Bin
diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c index d14e95c9dc..80d76f0181 100644 --- a/target/riscv/cpu.c +++ b/target/riscv/cpu.c @@ -382,6 +382,7 @@ static void riscv_cpu_dump_state(CPUState *cs, FILE *f, int flags) CSR_MHARTID, CSR_MSTATUS, CSR_MSTATUSH, + CSR_SSTATUS, CSR_HSTATUS, CSR_VSSTATUS, CSR_MIP,
sstatus register dump is currently missing in riscv_cpu_dump_state(). Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1332 Signed-off-by: Bin Meng <bmeng@tinylab.org> --- target/riscv/cpu.c | 1 + 1 file changed, 1 insertion(+)