soc:2008:stefanha:journal:week1 - Etherboot/gPXE Wiki

====== Differences ====== This shows you the differences between two versions of the page.

--- soc:2008:stefanha:journal:week1 [2008/06/04 01:04]
stefanha created
+++ soc:2008:stefanha:journal:week1 [2008/06/04 02:46] (current)
stefanha
@@ Line 1: / Line 1: @@
-==== Week 1 ====
+====== Stefan Hajnoczi: GDB Remote Debugging ======
+===== Journal Week 1 =====
 **Milestone:** Set up IDT and write an interrupt handler.
-=== Fri May 23 ===
+==== Fri May 23 ====
 Some notes after chatting with mdc and mcb30:
   * Place IDT code in ''arch/i386/transitions/librm.S'' - in similar places to ''lgdt'' and ''sgdt''.
@@ Line 9: / Line 11: @@
   * Source-level debugging and symbols should work (mostly) out-of-the-box due to ELF build.
-=== Sat May 24 ===
+==== Sat May 24 ====
 Git commit: [[http://git.etherboot.org/?p=people/stefanha/gpxe.git;a=commit;h=ac29ad53aff6e89f12bd5a163861d1afb1846049|ac29ad53aff6e89f12bd5a163861d1afb1846049]]
 Implemented an interrupt handler in ''arch/i386/transitions/librm.S''.  It currently sets ''eax'' to ''0xcafebabe'' and spins in an infinite loop.  Have tested that it is working using QEMU.
-=== Sun May 25 ===
+==== Sun May 25 ====
 Git commits: [[http://git.etherboot.org/?p=people/stefanha/gpxe.git;a=commit;h=12144ffbfadef9c6597f9ac754685223bb736368|12144ffbfadef9c6597f9ac754685223bb736368]], [[http://git.etherboot.org/?p=people/stefanha/gpxe.git;a=commit;h=1ff72edaa0c68966e1bc102ae5167d714eeb03e6|1ff72edaa0c68966e1bc102ae5167d714eeb03e6]], [[http://git.etherboot.org/?p=people/stefanha/gpxe.git;a=commit;h=c15542a614961acc1051296fc2367d1539db57ff|c15542a614961acc1051296fc2367d1539db57ff]]
@@ Line 23: / Line 25: @@
 Each interrupt is mapped onto a POSIX signal number (e.g. ''SIGSEGV'').  The GDB protocol communicates these numbers when reporting that execution was interrupted.
-=== Mon May 26 ===
+==== Mon May 26 ====
 Git commit: [[http://git.etherboot.org/?p=people/stefanha/gpxe.git;a=commit;h=f6c6b14468fffff0cf55df77ee7bb796113bcb4a|f6c6b14468fffff0cf55df77ee7bb796113bcb4a]], [[http://git.etherboot.org/?p=people/stefanha/gpxe.git;a=commit;h=6f8c3b03af1fa4733958a0ad66496a0acc8ce882|6f8c3b03af1fa4733958a0ad66496a0acc8ce882]]
@@ Line 30: / Line 32: @@
 The interrupt handler calls ''gdbstub_handler(regs)'', where ''regs'' is a pointer to the register snapshot.  The GDB stub may change the values in the register snapshot.  When the interrupt handler exits, it applies the snapshot to the CPU state.  **Changing ''ESP'' is currently not supported**, since it is more difficult to implement and we do not anticipate it ever being changed.
-=== Tue May 27 ===
+==== Tue May 27 ====
 Git commit: [[http://git.etherboot.org/?p=people/stefanha/gpxe.git;a=commit;h=d1e823a19d9c847fb7a965f8fbb9345f68875c3a|d1e823a19d9c847fb7a965f8fbb9345f68875c3a]]
@@ Line 60: / Line 62: @@
 </code>
-=== Wed May 28 ===
+==== Wed May 28 ====
 Git commit: [[http://git.etherboot.org/?p=people/stefanha/gpxe.git;a=commit;h=6f5d000a673209278400b9a04e12ee36cab07d28|6f5d000a673209278400b9a04e12ee36cab07d28]]
@@ Line 71: / Line 73: @@
 I am not sure if this is the best solution, but I'll use it for a while and see how effective it is.
-=== Thur May 29 ===
+==== Thur May 29 ====
 Git commits: [[http://git.etherboot.org/?p=people/stefanha/gpxe.git;a=commit;h=d828b65e7182372fdf3f9174f76a6d31341d16a9|d828b65e7182372fdf3f9174f76a6d31341d16a9]], [[http://git.etherboot.org/?p=people/stefanha/gpxe.git;a=commit;h=00f6bbbb61348865d57ebc979617f5f962bd037c|00f6bbbb61348865d57ebc979617f5f962bd037c]]
@@ Line 80: / Line 82: @@
 Implemented retransmit support if GDB sends NACK after receiving a corrupted reply from the GDB stub.
-=== Fri May 30 ===
+==== Fri May 30 ====
 Had the weekly mentor meeting today with mdc.  The aim for next week is **to push the GDB stub into mainline**.  Mainline support will make using the GDB stub easy for developers and advanced users.  I hope that others will find debugging useful way to develop faster.  Mainline exposure will also help the GDB stub to improve.
@@ Line 92: / Line 94: @@
 Having a test suite is important to me because I want to have the freedom of experimenting with the GDB stub code without worrying about breaking things.  The test suite will make sure I don't introduce regressions.
-=== Sat May 31 ===
+==== Sat May 31 ====
 Git commit: [[http://git.etherboot.org/?p=people/stefanha/gpxe.git;a=commit;h=42838a3f3147236be9a586dabc3524dc128235ec|42838a3f3147236be9a586dabc3524dc128235ec]], [[http://git.etherboot.org/?p=people/stefanha/gpxe.git;a=commitdiff;h=95b94a699fb0e62613885f0936890e902f624ae0|95b94a699fb0e62613885f0936890e902f624ae0]]
@@ Line 103: / Line 105: @@
 A neat solution proposed by mdc was to have ''config-local.h''.  This file never gets checked in to git and can override the defaults in ''config.h''.  I have implemented this idea by adding support for the ''@TRYSOURCE'' directive to ''util/mkconfig.pl''.  The main ''config.h'' now tries to source ''config-local.h'' if it exists.
-=== Sun Jun 1 ===
+==== Sun Jun 1 ====
 I played with the [[http://sourceforge.net/mailarchive/forum.php?thread_name=20080527223721.GA7464%40motherbox.xtech.com.ar&forum_name=etherboot-developers|ipv4_arp_check hang bug]].  This was a great test for the GDB stub.  The GDB stub worked well except for the usual issues with optimized code.
@@ Line 111: / Line 113: @@
 Thinking about this class of bugs also suggests having a default watchpoint on 0x00000000 whenever gPXE is built with ''GDBSTUB''.  A memory read or write to 0x00000000 will result in breaking into the debugger.  This is like the ''NULL_TRAP'' feature on steroids :-).
+===== Next week =====
+[[.:week2|On to Week 2]]!

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