pkg/kernel: allow to split full make output

Currently kernel build failures are insanely verbose
(contain full kernel build output) and there is no
way to separate short descriptions from full output.
Make it possible.
Also try to extract failure root cause froom build log.
Use this in pkg/bisect to not pollute log on build failures.

Update #501

1 files changed, 2 insertions, 2 deletions

diff --git a/pkg/instance/instance.go b/pkg/instance/instance.go
index ae94c265f..84e3c518d 100644
--- a/pkg/instance/instance.go
+++ b/pkg/instance/instance.go
@@ -81,14 +81,14 @@ func (env *Env) BuildSyzkaller(repo, commit string) error {
 func (env *Env) BuildKernel(compilerBin, userspaceDir, cmdlineFile, sysctlFile string, kernelConfig []byte) error {
 	cfg := env.cfg
 	if err := kernel.Build(cfg.KernelSrc, compilerBin, kernelConfig); err != nil {
-		return fmt.Errorf("kernel build failed: %v", err)
+		return osutil.PrependContext("kernel build failed", err)
 	}
 	cfg.Vmlinux = filepath.Join(cfg.KernelSrc, "vmlinux")
 	cfg.Image = filepath.Join(cfg.Workdir, "syz-image")
 	cfg.SSHKey = filepath.Join(cfg.Workdir, "syz-key")
 	if err := kernel.CreateImage(cfg.TargetOS, cfg.TargetVMArch, cfg.Type,
 		cfg.KernelSrc, userspaceDir, cmdlineFile, sysctlFile, cfg.Image, cfg.SSHKey); err != nil {
-		return fmt.Errorf("image build failed: %v", err)
+		return osutil.PrependContext("image build failed", err)
 	}
 	return nil
 }