| Message ID | 20210307202607.27745-2-mark.cave-ayland@ilande.co.uk |
|---|---|
| State | New |
| Headers | show |
| Series | target/m68k: MacOS related fixes | expand |
Le 07/03/2021 à 21:26, Mark Cave-Ayland a écrit : > If a NuBus slot doesn't contain a card, the Quadra hardware generates a physical > bus error if the CPU attempts to access the slot address space. Both Linux and > MacOS use a separate bus error handler during NuBus accesses in order to detect > and recover when addressing empty slots. > > According to the MC68040 users manual the ATC bit of the SSW is used to > distinguish between ATC faults and physical bus errors. MacOS specifically checks > the stack frame generated by a NuBus error and panics if the SSW ATC bit is set. > > Update m68k_cpu_transaction_failed() so that the SSW ATC bit is not set if the > memory API returns MEMTX_DECODE_ERROR which will be used to indicate that an > access to an empty NuBus slot occurred. > > Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> > --- > target/m68k/op_helper.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/target/m68k/op_helper.c b/target/m68k/op_helper.c > index 202498deb5..59a6448296 100644 > --- a/target/m68k/op_helper.c > +++ b/target/m68k/op_helper.c > @@ -468,7 +468,17 @@ void m68k_cpu_transaction_failed(CPUState *cs, hwaddr physaddr, vaddr addr, > > if (m68k_feature(env, M68K_FEATURE_M68040)) { > env->mmu.mmusr = 0; > - env->mmu.ssw |= M68K_ATC_040; > + > + /* > + * According to the MC68040 users manual the ATC bit of the SSW is > + * used to distinguish between ATC faults and physical bus errors. > + * In the case of a bus error e.g. during nubus read from an empty > + * slot this bit should not be set > + */ > + if (response != MEMTX_DECODE_ERROR) { > + env->mmu.ssw |= M68K_ATC_040; > + } > + > /* FIXME: manage MMU table access error */ > env->mmu.ssw &= ~M68K_TM_040; > if (env->sr & SR_S) { /* SUPERVISOR */ > Reviewed-by: Laurent Vivier <laurent@vivier.eu>
diff --git a/target/m68k/op_helper.c b/target/m68k/op_helper.c index 202498deb5..59a6448296 100644 --- a/target/m68k/op_helper.c +++ b/target/m68k/op_helper.c @@ -468,7 +468,17 @@ void m68k_cpu_transaction_failed(CPUState *cs, hwaddr physaddr, vaddr addr, if (m68k_feature(env, M68K_FEATURE_M68040)) { env->mmu.mmusr = 0; - env->mmu.ssw |= M68K_ATC_040; + + /* + * According to the MC68040 users manual the ATC bit of the SSW is + * used to distinguish between ATC faults and physical bus errors. + * In the case of a bus error e.g. during nubus read from an empty + * slot this bit should not be set + */ + if (response != MEMTX_DECODE_ERROR) { + env->mmu.ssw |= M68K_ATC_040; + } + /* FIXME: manage MMU table access error */ env->mmu.ssw &= ~M68K_TM_040; if (env->sr & SR_S) { /* SUPERVISOR */
If a NuBus slot doesn't contain a card, the Quadra hardware generates a physical bus error if the CPU attempts to access the slot address space. Both Linux and MacOS use a separate bus error handler during NuBus accesses in order to detect and recover when addressing empty slots. According to the MC68040 users manual the ATC bit of the SSW is used to distinguish between ATC faults and physical bus errors. MacOS specifically checks the stack frame generated by a NuBus error and panics if the SSW ATC bit is set. Update m68k_cpu_transaction_failed() so that the SSW ATC bit is not set if the memory API returns MEMTX_DECODE_ERROR which will be used to indicate that an access to an empty NuBus slot occurred. Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> --- target/m68k/op_helper.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)