Hi,
On Tue, Jun 18, 2024 at 4:38 AM Daniel Thompson
<daniel.thompson@linaro.org> wrote:
>
> On Mon, Jun 17, 2024 at 05:34:40PM -0700, Douglas Anderson wrote:
> > The "mdW" and "mdWcN" generally lets the user control more carefully
> > what word size we display memory in and exactly how many words should
> > be displayed. Specifically, "md4" says to display memory w/ 4
> > bytes-per word and "md4c6" says to display 6 words of memory w/
> > 4-bytes-per word.
> >
> > The kdb "md" implementation has a special rule for when "W" is 0. In
> > this case:
> > * If you run with "W" == 0 and you've never run a kdb "md" command
> > this reboot then it will pick 4 bytes-per-word, ignoring the normal
> > default from the environment.
> > * If you run with "W" == 0 and you've run a kdb "md" command this
> > reboot then it will pick up the bytes per word of the last command.
> >
> > As an example:
> > [1]kdb> md2 0xffffff80c8e2b280 1
> > 0xffffff80c8e2b280 0200 0000 0000 0000 e000 8235 0000 0000 ...
> > [1]kdb> md0 0xffffff80c8e2b280 1
> > 0xffffff80c8e2b280 0200 0000 0000 0000 e000 8235 0000 0000 ...
> > [1]kdb> md 0xffffff80c8e2b280 1
> > 0xffffff80c8e2b280 0000000000000200 000000008235e000 ...
> > [1]kdb> md0 0xffffff80c8e2b280 1
> > 0xffffff80c8e2b280 0000000000000200 000000008235e000 ...
> >
> > This doesn't seem like particularly useful behavior and adds a bunch
> > of complexity to the arg parsing. Remove it.
> >
> > Signed-off-by: Douglas Anderson <dianders@chromium.org>
> > ---
> >
> > kernel/debug/kdb/kdb_main.c | 5 -----
> > 1 file changed, 5 deletions(-)
> >
> > diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
> > index c013b014a7d3..700b4e355545 100644
> > --- a/kernel/debug/kdb/kdb_main.c
> > +++ b/kernel/debug/kdb/kdb_main.c
> > @@ -1611,11 +1611,6 @@ static int kdb_md(int argc, const char **argv)
> >
> > if (isdigit(argv[0][2])) {
> > bytesperword = (int)(argv[0][2] - '0');
> > - if (bytesperword == 0) {
> > - bytesperword = last_bytesperword;
> > - if (bytesperword == 0)
> > - bytesperword = 4;
> > - }
> > last_bytesperword = bytesperword;
> > repeat = mdcount * 16 / bytesperword;
>
> Isn't this now a divide-by-zero?
Dang, you're right. It goes away in a later patch, though, since we
stop re-calculating everything until the end when things are
validated. I'll plan to reorder this patch to be after the patch
("kdb: In kdb_md() make `repeat` and `mdcount` calculations more
obvious").