Hi Gautam, Thanks for taking a look. Please find my response inline below:
On 2026/05/08 10:50 AM, Gautam Menghani wrote: > On Mon, May 04, 2026 at 07:13:44PM +0530, Amit Machhiwal wrote: > > GCC 16 tightens diagnostics around const correctness and now correctly > > rejects attempts to modify strings referenced through const-qualified > > pointers. In kvm_ppc_register_host_cpu_type(), ppc_cpu_aliases[i].model > > is defined as const char *, but the code was using strstr() on it and > > then modifying the returned pointer in-place to strip > > POWERPC_CPU_TYPE_SUFFIX. > > > > This results in a write through a pointer derived from const data, > > triggering a build failure with GCC 16: > > > > error: assignment discards 'const' qualifier from pointer target type > > [-Werror=discarded-qualifiers] > > suffix = strstr(ppc_cpu_aliases[i].model, POWERPC_CPU_TYPE_SUFFIX); > > ^ > > > > Fix this by duplicating the model string into a mutable buffer using > > g_strdup(), storing it in the alias table, and then performing the > > suffix truncation on the mutable copy. > > > > This preserves the existing behavior while avoiding modification of > > const data and ensures compatibility with newer compilers. > > > > No functional change intended. > > > > Signed-off-by: Amit Machhiwal <[email protected]> > > --- > > target/ppc/kvm.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c > > index 25c28ad089c6..e71e5c0117da 100644 > > --- a/target/ppc/kvm.c > > +++ b/target/ppc/kvm.c > > @@ -2654,10 +2654,12 @@ static int kvm_ppc_register_host_cpu_type(void) > > dc = DEVICE_CLASS(ppc_cpu_get_family_class(pvr_pcc)); > > for (i = 0; ppc_cpu_aliases[i].alias != NULL; i++) { > > if (g_ascii_strcasecmp(ppc_cpu_aliases[i].alias, dc->desc) == 0) { > > + char *model; > > char *suffix; > > > > - ppc_cpu_aliases[i].model = g_strdup(object_class_get_name(oc)); > > - suffix = strstr(ppc_cpu_aliases[i].model, > > POWERPC_CPU_TYPE_SUFFIX); > > + model = g_strdup(object_class_get_name(oc)); > > + ppc_cpu_aliases[i].model = model; > > + suffix = strstr(model, POWERPC_CPU_TYPE_SUFFIX); > > if (suffix) { > > *suffix = 0; > > } > > > > A const char * variable is ideally supposed to point to an immutable > string. But even with this fix, the string that > "ppc_cpu_aliases[i].model" points to is being changed after assignment. Thanks, I get your point. The write in my version is to the mutable buffer returned by g_strdup(), so it is not strictly a const write. I had originally trimmed the duplicated buffer before assigning it to ppc_cpu_aliases[i].model, but later reordered it to stay closer to the existing flow. Still, I agree with the suggested cleaner ordering. I will update it in the next revision. Thanks, Amit > Would the below diff (untested) be a better fix? > > diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c > index 41bd03ec2a..a84e4b4636 100644 > --- a/target/ppc/kvm.c > +++ b/target/ppc/kvm.c > @@ -2654,13 +2654,14 @@ static int kvm_ppc_register_host_cpu_type(void) > dc = DEVICE_CLASS(ppc_cpu_get_family_class(pvr_pcc)); > for (i = 0; ppc_cpu_aliases[i].alias != NULL; i++) { > if (strcasecmp(ppc_cpu_aliases[i].alias, dc->desc) == 0) { > - char *suffix; > + char *suffix, *model; > > - ppc_cpu_aliases[i].model = g_strdup(object_class_get_name(oc)); > - suffix = strstr(ppc_cpu_aliases[i].model, > POWERPC_CPU_TYPE_SUFFIX); > + model = g_strdup(object_class_get_name(oc)); > + suffix = strstr(model, POWERPC_CPU_TYPE_SUFFIX); > if (suffix) { > *suffix = 0; > } > + ppc_cpu_aliases[i].model = model; > break; > } > }
