misc/nacl: add debugging instructions

LGTM=dave, minux
R=golang-codereviews, dave, minux
CC=golang-codereviews, rsc
https://golang.org/cl/122570043

diff --git a/misc/nacl/README b/misc/nacl/README
index 6f149f8ac86448973a2759790e97725c1e48cadf..2044b356b65476a4081762603ff6f8742382fd3a 100644 (file)
--- a/misc/nacl/README
+++ b/misc/nacl/README
@@ -37,7 +37,7 @@ sdk. These are released every 6-8 weeks, in line with Chrome releases.
        % cd /opt/nacl_sdk
        % ./naclsdk update
 
-At this time pepper_33 is the stable version. If naclsdk downloads a later
+At this time pepper_34 is the stable version. If naclsdk downloads a later
 version, please adjust accordingly. As of June 2014, only the canary sdk
 provides support for nacl/arm.
 
@@ -45,8 +45,8 @@ The cmd/go helper scripts expect that the loaders sel_ldr_{x86_{32,64},arm} and
 nacl_helper_bootstrap_arm are in your path. I find it easiest to make a symlink
 from the NaCl distribution to my $GOPATH/bin directory.
 
-       % ln -nfs /opt/nacl_sdk/pepper_33/tools/sel_ldr_x86_32 $GOPATH/bin/sel_ldr_x86_32
-       % ln -nfs /opt/nacl_sdk/pepper_33/tools/sel_ldr_x86_64 $GOPATH/bin/sel_ldr_x86_64
+       % ln -nfs /opt/nacl_sdk/pepper_34/tools/sel_ldr_x86_32 $GOPATH/bin/sel_ldr_x86_32
+       % ln -nfs /opt/nacl_sdk/pepper_34/tools/sel_ldr_x86_64 $GOPATH/bin/sel_ldr_x86_64
        % ln -nfs /opt/nacl_sdk/pepper_canary/tools/sel_ldr_arm $GOPATH/bin/sel_ldr_arm
 
 Additionally, for NaCl/ARM only:
@@ -92,3 +92,31 @@ tests.
        % cd go/src
        % env GOARCH=amd64p32 ./nacltest.bash
 
+Debugging
+---------
+
+Assuming that you have built nacl/amd64p32 binary ./mybin and can run as:
+
+       % sel_ldr_x86_64 -l /dev/null -S -e ./mybin
+
+Create the nacl manifest file mybin.manifest with the following contents:
+
+       { "program": { "x86-64": { "url": "mybin" } } }
+
+url is the path to the binary relative to the manifest file.
+Then, run the program as:
+
+       % sel_ldr_x86_64 -g -l /dev/null -S -e ./mybin
+
+The -g flag instructs the loader to stop at startup. Then, in another console:
+
+       % /opt/nacl_sdk/pepper_34/toolchain/linux_x86_glibc/bin/x86_64-nacl-gdb
+       % nacl-manifest mybin.manifest
+       % target remote :4014
+
+If you see that the program is stopped in _rt0_amd64p32_nacl, then symbols are
+loaded successfully and you can type 'c' to start the program.
+Next time you can automate it as:
+
+       % /opt/nacl_sdk/pepper_34/toolchain/linux_x86_glibc/bin/x86_64-nacl-gdb \
+               -ex 'nacl-manifest mybin.manifest' -ex 'target remote :4014'