On Tue, Jan 11, 2022 at 12:21:42PM +0000, Peter Maydell wrote: > On Tue, 11 Jan 2022 at 10:54, zhenwei pi <pizhen...@bytedance.com> wrote: > > > > A device of USB video class usually uses larger desc structure, so > > use larger buffer to avoid failure. (dev-video.c is ready) > > > > Allocating memory dynamically by g_malloc of the orignal version of > > this change, Philippe suggested just using the stack. Test the two > > versions of qemu binary, the size of stack gets no change. > > > > CC: Philippe Mathieu-Daudé <f4...@amsat.org> > > Signed-off-by: zhenwei pi <pizhen...@bytedance.com> > > --- > > hw/usb/desc.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/hw/usb/desc.c b/hw/usb/desc.c > > index 8b6eaea407..57d2aedba1 100644 > > --- a/hw/usb/desc.c > > +++ b/hw/usb/desc.c > > @@ -632,7 +632,7 @@ int usb_desc_get_descriptor(USBDevice *dev, USBPacket > > *p, > > bool msos = (dev->flags & (1 << USB_DEV_FLAG_MSOS_DESC_IN_USE)); > > const USBDesc *desc = usb_device_get_usb_desc(dev); > > const USBDescDevice *other_dev; > > - uint8_t buf[256]; > > + uint8_t buf[8192]; > > uint8_t type = value >> 8; > > uint8_t index = value & 0xff; > > int flags, ret = -1; > > I think 8K is too large to be allocating as an array on > the stack, so if we need this buffer to be larger we should > switch to some other allocation strategy for it.
IIUC, querying USB device descriptors is not a hot path, so using heap allocation feels sufficient. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
