OpenSBI: Boot HART ISA display

[Damien Le Moal]

On Tue, 2020-09-29 at 13:38 -0700, Atish Patra wrote:
> On Tue, Sep 29, 2020 at 12:38 PM Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> > On 9/29/20 9:05 PM, Atish Patra wrote:
> > > On Mon, Sep 28, 2020 at 3:18 AM Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> > > > Hello Atish,
> > > > 
> > > > on the Kendryte 210 MaixDuino the OpenSBI output line
> > > > 
> > > > Boot HART ISA       : rv64cicacsidcacsi
> > > > 
> > > > looks a bit strange to me (see full output at the end of the mail).
> > > 
> > > Yeah. It doesn't make any sense.
> > > 
> > > > Assuming that the characters after rv64 are related to extensions I
> > > > would expect every letter appearing only once.
> > > > 
> > > 
> > > That's correct. See 3.1.1. Machine ISA Register misa in priv spec.
> > > 
> > > > I tried to add sbi_printf() statements to lib/sbi/riscv_asm.c but they
> > > > do not print out correctly.
> > > > 
> > > > After the following change:
> > > > 
> > > > diff --git a/lib/sbi/riscv_asm.c b/lib/sbi/riscv_asm.c
> > > > index 8c54c11..a0c95a2 100644
> > > > --- a/lib/sbi/riscv_asm.c
> > > > +++ b/lib/sbi/riscv_asm.c
> > > > @@ -81,7 +81,7 @@ void misa_string(int xlen, char *out, unsigned int out_sz)
> > > > 
> > > >         for (i = 0; i < array_size(valid_isa_order) && (pos < out_sz);
> > > > i++) {
> > > >                 if (misa_extension_imp(valid_isa_order[i]))
> > > > -                       out[pos++] = valid_isa_order[i];
> > > > +                       out[pos++] = '0' + i;
> > > >         }
> > > > 
> > > >         if (pos < out_sz)
> > > > 
> > > > the output becomes
> > > > 
> > > > Boot HART ISA       : rv6403567;<@BCDHI
> > > > 
> > > > I am clueless why valid_isa_order[i] is not evaluated correctly.
> > > > 
> > > > When my changes are:
> > > > 
> > > > diff --git a/lib/sbi/riscv_asm.c b/lib/sbi/riscv_asm.c
> > > > index 8c54c11..b1bbfc4 100644
> > > > --- a/lib/sbi/riscv_asm.c
> > > > +++ b/lib/sbi/riscv_asm.c
> > > > @@ -12,6 +12,8 @@
> > > >  #include <sbi/sbi_error.h>
> > > >  #include <sbi/sbi_platform.h>
> > > > 
> > > > +static const char valid_isa_order[] = "iemafdqclbjtpvnsuhkorwxyzg";
> > > > +
> > > >  /* determine CPU extension, return non-zero support */
> > > >  int misa_extension_imp(char ext)
> > > >  {
> > > > @@ -52,7 +54,6 @@ int misa_xlen(void)
> > > >  void misa_string(int xlen, char *out, unsigned int out_sz)
> > > >  {
> > > >         unsigned int i, pos = 0;
> > > > -       const char valid_isa_order[] = "iemafdqclbjtpvnsuhkorwxyzg";
> > > > 
> > > >         if (!out)
> > > >                 return;
> > > > 
> > > > the output is:
> > > > 
> > > > Boot HART ISA       : rv64imafdcsu
> > > > 
> > > 
> > > That's odd. Why does declaring valid_isa_order as static solve the issue ?
> > > 
> > > Can you print the "misa" in misa_extension_imp () ?
> > > Just a guess: What if misa is not read correctly ?
> > 
> > No matter which values misa_extension_imp() returns we should only see
> > extension ID letters in the correct sequence.
> > 
> 
> You are correct.
> 
> > "rv64cicacsidcacsi" is incorrect for any value of misa.
> > 
> > The interesting thing is that printf statements for strings that I
> > placed for debugging in misa_string() did not print correctly. Something
> > is going wrong here with strings.
> > 
> 
> + Damien
> 
> I just remembered Damien was facing a similar issue on Kendryte while
> running the test payload where
> it would not work if a string is used but worked fine if a single
> character is printed in a loop.
> 
> @Damien : Did you figure out the cause for that issue you were seeing?

Here is what I get:


OpenSBI v0.8-29-g7701ea1
   ____                    _____ ____ _____
  / __ \                  / ____|  _ \_   _|
 | |  | |_ __   ___ _ __ | (___ | |_) || |
 | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
 | |__| | |_) |  __/ | | |____) | |_) || |_
  \____/| .__/ \___|_| |_|_____/|____/_____|
        | |
        |_|

Platform Name       : Kendryte K210
Platform Features   : timer
Platform HART Count : 2
Boot HART ID        : 0
Boot HART ISA       : rv64fucicacsidc
BOOT HART Features  : none
BOOT HART PMP Count : 0
BOOT HART MHPM Count: 0
Firmware Base       : 0x80000000
Firmware Size       : 96 KB
Runtime SBI Version : 0.2

MIDELEG : 0x0000000000000222
MEDELEG : 0x0000000000000109

So different fuzziness for the MISA string, wrong too.
And no prints from the test payload either, so definitely wrong.

However, I am getting warnings on the DTS. Something wrong there that may
impact the serial. Looking into it.

> 
> > It might be that some function is overwriting the area where the strings
> > are stored, e.g via the stack.
> > 
> > Best regards
> > 
> > Heinrich
> > 
> > > > I disassembled build/lib/sbi/riscv_asm.o but could not find a problem.
> > > > 
> > > > Do you have a suggestion how to analyze this further?
> > > > 
> > > > Best regards
> > > > 
> > > > Heinrich
> > > > 
> > > > 
> > > > 
> > > > OpenSBI v0.8-29-g7701ea1
> > > >    ____                    _____ ____ _____
> > > >   / __ \                  / ____|  _ \_   _|
> > > >  | |  | |_ __   ___ _ __ | (___ | |_) || |
> > > >  | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
> > > >  | |__| | |_) |  __/ | | |____) | |_) || |_
> > > >   \____/| .__/ \___|_| |_|_____/|____/_____|
> > > >         | |
> > > >         |_|
> > > > 
> > > > Platform Name       : Kendryte K210
> > > > Platform Features   : timer
> > > > Platform HART Count : 2
> > > > Boot HART ID        : 0
> > > > Boot HART ISA       : rv64cicacsidcacsi
> > > > BOOT HART Features  : none
> > > > BOOT HART PMP Count : 0
> > > > BOOT HART MHPM Count: 0
> > > > Firmware Base       : 0x80000000
> > > > Firmware Size       : 100 KB
> > > > Runtime SBI Version : 0.2
> > > > 
> > > > MIDELEG : 0x0000000000000222
> > > > MEDELEG : 0x0000000000000109
> > > > 
> > > > 
> > > > --
> > > > opensbi mailing list
> > > > opensbi at lists.infradead.org
> > > > http://lists.infradead.org/mailman/listinfo/opensbi
> > > 
> > > 
> 
> 

-- 
Damien Le Moal
Western Digital