Peter Maydell <peter.mayd...@linaro.org> writes: > On Mon, 13 Jul 2020 at 19:32, Philippe Mathieu-Daudé <f4...@amsat.org> wrote: >> >> QEMU allows to create SD card with unrealistic sizes. This could >> work, but some guests (at least Linux) consider sizes that are not >> a power of 2 as a firmware bug and fix the card size to the next >> power of 2. >> > >> + error_setg(errp, "Invalid SD card size: %s", blk_size_str); >> + g_free(blk_size_str); >> + >> + blk_size_str = size_to_str(blk_size_aligned); >> + error_append_hint(errp, >> + "SD card size has to be a power of 2, e.g. >> %s.\n" >> + "You can resize disk images with " >> + "'qemu-img resize <imagefile> <new-size>'\n" >> + "(note that this will lose data if you make >> the " >> + "image smaller than it currently is).\n", >> + blk_size_str); >> + g_free(blk_size_str); > > Some places that create multi-line hints with error_append_hint() > do it by calling it once per line, eg in target/arm/cpu64.c: > error_setg(errp, "cannot disable sve128"); > error_append_hint(errp, "Disabling sve128 results in all " > "vector lengths being disabled.\n"); > error_append_hint(errp, "With SVE enabled, at least one " > "vector length must be enabled.\n"); > > Some places don't, eg in block/vhdx-log.c: > error_append_hint(errp, "To replay the log, run:\n" > "qemu-img check -r all '%s'\n", > bs->filename);
Both fine. > Most places terminate with a '\n', but some places don't, eg > crypto/block-luks.c: > error_append_hint(errp, "Failed to write to keyslot %i", keyslot); > return -1; This is a bug. > The documentation says > * May be called multiple times. The resulting hint should end with a > * newline. > > which isn't very clear -- you can call it multiple times, but > must you, if it's multiline? If that was required, my doc comment would demand it. > I assume that "should end with a newline" means "must end > with a newline", and places like block-luks.c are bugs. If you construct a hint with multiple calls, individual calls need not terminate with a newline, but the resulting hint still should. I readily admit that my doc comments sometimes require a "lawyerly" reading :) > Markus, do you know what the intended API here is? > > It looks like the implementation just tacks the hint > string onto the end of any existing hint string, in > which case multiple-line strings are fine and the same > behaviour as calling the function multiple times. That's the intended behavior. > (I had assumed we might be accumulating an array of strings, > or requiring multiline strings to be multiple calls so we > could have the argument not need to be \n-terminated, > to match error_setg(), but both those assumptions > are obviously wrong.) Would also be workable, if slightly less flexible. Yes, error_setg() and error_append_hint() differ on newlines. error_setg() constructs an error message. These get reported in a rigid format that does not afford line breaks in the middle. error_append_hint() builds up a hint. Hints are free-form text. Embedded line breaks are fine. In both cases, I decided not to treat newline at the end any different from newlines anywhere else. Thus, no newlines at all with error_setg(), and newlines after every line including the last one with error_append_hint(). > Anyway, I guess this multiline-message usage is something > we do already and it will DTRT, so Correct. Hope this helps! > Reviewed-by: Peter Maydell <peter.mayd...@linaro.org> > > > thanks > -- PMM
