On Tue, Sep 22, 2026 at 09:15:23AM +0200, Sebastian Ramacher wrote:
> Source: snappy
> Version: 1.3.1-2
> Severity: serious
> Tags: ftbfs
> Justification: fails to build from source (but built successfully in the past)
> X-Debbugs-Cc: [email protected], [email protected]
> User: [email protected]
> Usertags: riscv64
>
> Dear maintainer,
>
> snappy FTBFS on riscv64:
>
> /usr/bin/riscv64-linux-gnu-g++ -I/build/reproducible-path/snappy-1.3.1/build
> -I/build/reproducible-path/snappy-1.3.1 -g -O2
> -ffile-prefix-map=/build/reproducible-path/snappy-1.3.1=.
> -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time
> -D_FORTIFY_SOURCE=2 -Wall -Wextra -Wno-sign-compare -fno-exceptions -O2 -g
> -DNDEBUG -std=gnu++17 -MD -MT CMakeFiles/snappy-static.dir/snappy.cc.o -MF
> CMakeFiles/snappy-static.dir/snappy.cc.o.d -o
> CMakeFiles/snappy-static.dir/snappy.cc.o -c
> /build/reproducible-path/snappy-1.3.1/snappy.cc
> /usr/bin/riscv64-linux-gnu-g++ -DHAVE_CONFIG_H -Dsnappy_EXPORTS
> -I/build/reproducible-path/snappy-1.3.1/build
> -I/build/reproducible-path/snappy-1.3.1 -g -O2
> -ffile-prefix-map=/build/reproducible-path/snappy-1.3.1=.
> -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time
> -D_FORTIFY_SOURCE=2 -Wall -Wextra -Wno-sign-compare -fno-exceptions -O2 -g
> -DNDEBUG -std=gnu++17 -fPIC -MD -MT CMakeFiles/snappy.dir/snappy.cc.o -MF
> CMakeFiles/snappy.dir/snappy.cc.o.d -o CMakeFiles/snappy.dir/snappy.cc.o -c
> /build/reproducible-path/snappy-1.3.1/snappy.cc
> /build/reproducible-path/snappy-1.3.1/snappy.cc: In function ‘void
> snappy::MemCopy64(char*, const void*, size_t)’:
> /build/reproducible-path/snappy-1.3.1/snappy.cc:1281:28: error: built-in
> function ‘__riscv_vsetvl_e8m2(remaining_bytes)’ requires the ‘v’ ISA extension
> 1281 | size_t vl = VSETVL_E8M2(remaining_bytes);
> /build/reproducible-path/snappy-1.3.1/snappy.cc:1283:33: error: this
> operation requires the RVV ISA extension
> 1283 | vuint8m2_t vec = VLE8_V_U8M2(src_ptr, vl);
> /build/reproducible-path/snappy-1.3.1/snappy.cc:1283:33: note: you can enable
> RVV using the command-line option ‘-march’, or by using the ‘target’
> attribute or pragma
> /build/reproducible-path/snappy-1.3.1/snappy.cc:1283:33: error: built-in
> function ‘__riscv_vle8_v_u8m2(src_ptr, vl)’ requires the ‘v’ ISA extension
> /build/reproducible-path/snappy-1.3.1/snappy.cc:1285:16: error: built-in
> function ‘__riscv_vse8_v_u8m2(dst_ptr, vec, vl)’ requires the ‘v’ ISA
> extension
> 1285 | VSE8_V_U8M2(dst_ptr, vec, vl);
> make[3]: *** [CMakeFiles/snappy.dir/build.make:124:
> CMakeFiles/snappy.dir/snappy.cc.o] Error 1
>
> See
> https://buildd.debian.org/status/fetch.php?pkg=snappy&arch=riscv64&ver=1.3.1-2&stamp=1790060158&raw=0
> for details.
The problem is:
-- Performing Test SNAPPY_RVV_1
-- Performing Test SNAPPY_RVV_1 - Success
Which has an interesting cause:
$ cat test.cc
#include <riscv_vector.h>
#include <stdint.h>
#include <stddef.h>
int main() {
uint8_t val = 3, dup[8];
size_t vl = __riscv_vsetvl_e8m1(8);
vuint8m1_t v = __riscv_vmv_v_x_u8m1(val, vl);
return 0;
}
$ g++ -Wall test.cc
test.cc: In function 'int main()':
test.cc:5:22: warning: unused variable 'dup' [-Wunused-variable]
5 | uint8_t val = 3, dup[8];
| ^~~
test.cc:7:16: warning: unused variable 'v' [-Wunused-variable]
7 | vuint8m1_t v = __riscv_vmv_v_x_u8m1(val, vl);
| ^
test.cc:6:36: error: built-in function '__riscv_vsetvl_e8m1(8)' requires the
'v' ISA extension
6 | size_t vl = __riscv_vsetvl_e8m1(8);
| ~~~~~~~~~~~~~~~~~~~^~~
test.cc:7:40: error: this operation requires the RVV ISA extension
7 | vuint8m1_t v = __riscv_vmv_v_x_u8m1(val, vl);
| ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~
test.cc:7:40: note: you can enable RVV using the command-line option '-march',
or by using the 'target' attribute or pragma
test.cc:7:40: error: built-in function '__riscv_vmv_v_x_u8m1(val, vl)' requires
the 'v' ISA extension
(sid_riscv64-dchroot)bunk@ricci:~/build$ g++ -Wall -O2 test.cc
test.cc: In function 'int main()':
test.cc:5:22: warning: unused variable 'dup' [-Wunused-variable]
5 | uint8_t val = 3, dup[8];
| ^~~
test.cc:7:16: warning: unused variable 'v' [-Wunused-variable]
7 | vuint8m1_t v = __riscv_vmv_v_x_u8m1(val, vl);
| ^
$
Removing the SNAPPY_RVV_1 block from CMakeLists.txt works around this issue.
> Cheers
cu
Adrian
